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About Google Book Search Google's mission is to organize the world's information and to make it universally accessible and useful. Google Book Search helps readers discover the world's books while helping authors and publishers reach new audiences. You can search through the full text of this book on the web at |http: //books .google .com/I TBANSACTIO i It (Ideological ^odetp CORNWALL. wuTtTVTJtv risneu^sr atK jsu ^% THK NINTH- I'iVJtT TUli FOIST I Varu." '■ 5IT THE ATABTllESTB OF THE SOfJIKTV. UIS. I TRANSACTIONS 07 THS BOTAL GEOLOGICAL SOCIETY OF CORNWALL. VOL. IX. PjLBT I. PLTXOrTH : WILLIAM B&KNDON AHD 80K, PRIMTF.RR, OKOKOK ATREKT. TRANSACTIONS OF THB i^opal iHeolosital ^otitt^ OF CORNWALL. INSTITUTED FEBRUARY 11th, 1814. VOLUME THE NINTH— PART THE FIRST. ** A knowledge of our subterranean wealth would be the means of furnishing greater opulence to the country than the acquisition of the mines of Mexico and Peru." President of the Board of Agriculture, PENZANCE : SOLD AT THE APARTMENTS OF THE SOCIETY. 1875. TABLE OF CONTENTS. ERRATA. Page vi. Page 3 Page 17 Page 25 Page 38 Page 42 Piige 47 Page 53 Page 64 Page 59 Page 60 Page 60 Page 63 iino 23, for " it" read *' a " in Hulamanmng. line 25, for " on " read " or." line 5, for " oride " read " oxide of tin" line 21, for " Crystallyanic" read " CrysUiUogenic" line 5, for " ^S'wk^A " read '' Smyth," line 7, for " ruggy " read '' niujS'6-z«6 " read '' Jfriib." line 5 from belosv, for ** dampfrriehl " read " Damp/mehl." VI. On the Occurrence of Metallic Ores with Garnet Rock. Note illustrating a series of Copper Ores from Belstohe Consols, Devon. By Wanngton W. Smyth, M.A., F.R.S., f.g.s. . . 38 VII. On some Fossils from Moimt Lebanon. By Alfred Lloyd Fox . 46 vin. Bemarks (with a list) on some of the Organic Remains of Cornwall in the Museum of the Royal Geological Society of Cornwall at Penzance. By C. W. Peach . . . . 49 vi Table of Contents. IX. PAGE On the Discovery of Organic Remains in the Hocks of Nelly's Cove, near Porthalla, and of some curious Organic-like Masses in a quarry near Hayle. By C. W. Peach . . 55 X. Some Observations on the Magnesit^ of Silesia. By Lovell Squire, jun., D. A. . . . ... 59 XI. The Geology of Lundy Island, with Map. By Nicholas Whitley. 71 XII. Remarkable Sea Waves, observed in Mount's Bay, Cornwall, April 24th, 1868. By John Jope Rogers . . . . 74 XIII. Notes on the Quartz Reefs or Lodes of Sandhurst, Victoria, Aus- tralia. By W. Nicholas . . ... 78 XIV. Memoiandum on the Discovery of Hazel-nuts in Tin Stream at St. Hilary. By Thomas Cornish . . . . 98 XV. Note on Chrome Iron in the Serpentine of the Lizard. By Richard Pearce, p.g.s. . . . ... 99 XVI. Note on a Granite Block at Hulamanning. By Richard James . 101 XVII. Memorandum on Pitchblende in Colorado. By Richard Pearce . lOi xvin. Note on Pitchblende in ComwalL By Richard Pearce . . 103 XIX. On Traces of Glacial Action on the Great Cairn, near Gorran Haven, Cornwall. By C. W. Peach . . . . 105 XX. The Geology of Penzance Bay and its Shores, with Map. By Nicholas Whitley . . . ... 109 Table of Contents. vii XXI. PAGE On the Bones of a Whale found at Pentuan, now in the Museum of the Royal (^logical Society of Cornwall. By William Henry Flower, P.R.S., &c. . . . . . 114 XXII. Some Kemarks on the Mining District of Yorke's Peninsula, South Australia. By Samuel Higgs, jun. . . . . 122 XXIII. Enquiry into the Nature of the Forces that have acted on tlie Formation and Elevation of the Land's End Granite. By Miss Elizabeth T. Came . . . .132 XXIV. Remarks on the Lode at Wheal Mary Ann, Menheniot, with Diagrams. By Clement Le Neve Foster, B.A., d.sc., f.g.s. . 152 XXV. Notice of a Vugh in St. Ives Consols Mines. By Captain John Gilbert . . . . ... 158 XXVI. Notice on Mount Bischoff, Tasmania. By William Wellington . 161 XXVII. On the Place and Mode of Occurrence of the Mineral Andrewsite. By C. Le Neve Foster . ... 163 Table of Contents. vii XXI. PAGE On the Bones of a Whale found at Pentuan, now in the Museum of the Royal Geological Society of Cornwall. By William Henry Flower, F.R.S., &c. . . . . . 114 XXII. Some Remarks on the Mining District of Yorke's Peninsula, South Australia. By Samuel Higgs, jun. . . . . 122 XXIII. Enquiry into the Nature of the Forces that have acted on the Formation and Elevation of the Land's End Granite. By Miss Elizabeth T. Came . . . .132 XXIV. Remarks on the Lode at Wheal Mary Ann, Menheniot, with Diagrams. By Clement Le Neve Foster, b.a., d.bc., p.g.s. . 152 XXV. Notice of a Vugh in St. Ives Consols Mines. By Captain John Gilbert . . . . ... 158 XXVI. Notice on Moimt Bischoff, Tasmania. By William Wellington . 161 xxvn. On the Place and Mode of Occurrence of the Mineral Andrewsite. By C. Le Neve Foster . . ... 163 ON TRANSITION AND METAMORPHOSIS OF ROCKS IN THE LAND'S END DISTRICT. By Miss Elizabeth T. Carne. SFORE we notice the transitions by which all these cks are connected with one another, it may be well point out the distinguishing features of the rocks emselves. Amidst much subordinate variety, there e five well-marked formations in our western dis- ict — a district which we will define by drawing a le from Hayle to Marazion. 1st. Granite. 2nd. Hornblende and actinolite rock, and green- one. These vary but little in their composition; at they have two distinct types in external character, ny one walking through the fields from Paul to ewlyn Clifi* may notice large blocks of hard, heavy, ilk-coloured stone in the hedges, which on fracture low a peculiar glistening surface of a greenish-black >lour. This is hornblende rock. A broad band of runs from Mousehole and Penlee Point northward Paul Hill, and it is almost the only place where it VOL. IX. B 3 On Transition and Metamorphosis of Rocks is found south of the granite, though it is not un- frequent in St. Just, Zennor, and St. Ives.* The more common greenstone is the hard blue stone generally used to mend our roads. It is well marked in Lariggan rocks, in the larger masses near the gas-works, in the foundation of Chyandour, in the quarry up the Coombe Lane, at Tolcarn and Gul- val Cam. It is said to be a compound of hornblende and felspar; but in this district the hornblende is often mixed with or superseded by actinolite, and the felspar by axinite.f 8rd. Purple killas. This is a rock hard to de- scribe, yet very strongly marked by its pinkish-purple tint. It is sometimes compact and hard ; sometimes laminated, splitting like clay-slate ; sometimes spotted with dull dark spots; but these varieties pass so readily into each other as to be easily traced. The harbour at Newlyn is full of beds of this rock, and the southern jetty there is built on it. It also forms the old quarry just opposite Newlyn Church, and occurs in patches on the rocks between Newlyn and Penlee Point. J 4th. A felspathic rock, varying so widely that it can only be described as possessing a large excess of felspar. This rock extends several hundred yards along the shore beyond the southern jetty at Newlyn in soft and hard, light and dark varieties, inextricably • This is the hornblende rock of Dr. Forbes, the fpreenstone of ^' BoASB. — Oeol, Tram, of Cornwall^ vol. ii. 261 ; vol. iv. 393-403. f This is the greenstone of Dr. Forbbs, the greenstone and actinolite- rock of Dr. Boasb. X This is the slaty -felspar of Dr. Forbes, the comubeanite of Dr. Boas'* in the Land's End Dtstrict. 3 nixed with purple killas, actinolite, &c. Another •orm of felspathic rock is found in the so-called elvan- 3ourse at Polmenor, which lies open in a pit by the roadside near the farm-house. A third form, massive ind very hard, is to be seen in the elvan-course that runs through the Chimney Rock.* 5th. Finally, there is a well-marked rock which, is its two varieties may be best studied in the cliffs beyond the Lelant ferry, I will call the Lelant rock. [ do not know its boundary northward ; but I have a specimen from St Ives Island and St. Ives Consols Kline. At Porthminster Point (south of St Ives) it forms the upper part of the cliffs, and further south, beyond Carrickgladden, the whole of them, extending to Lelant village, and across Ihe water to Phillack To wans and to Hayle Foundry and railway cuttings. It is found at Orowlas railway cutting; also in an excavation for building formerly made near Mara- zion turnpike, and on the sea-shore east of Marazion. I presume, therefore, that it stretches across the country from St Ives to Marazion, constituting the unaltered Devonian beds of the Ordnance map. In structure it is evidently sedimentary, occurring at Lelant in layers on beds varying in thickness from * This formation is, I presume, the felsparite of Dr. Boasb, the compact felspar of Dr. Fobbes. Geol. Trans, of Cornwall, iv. 375; ii. 251. I was for a long time greatly perplexed and milled by Dr. Fobbes' statement that slaty-felspar is "a rock apparently of the same composition as compact felspar, or only with the addition of a very small portion of mica, with a distinct slaty structure." I do not doubt that purple killas and felsparite are closely connected; but they are not "apparently so." The appearance of the two rocks is widely dififerent ; and until I met with the intermediate forma I could nerer identify Dr. Fobbes* slaty- felspar. B 2 4 On Transition and Metamorphosis of Rocks an inch to a couple of feet, dipping to the S.E., and often regularly alternate in coarse and fine grain. The coarse-grained is compact, granular, of a green- ish-grey colour, sprinkled with minute white specks, which give it a pepper-and-salt aspect. The fine- grained is sometimes a dull grey slate, or a glossy grey shale ; indeed the colour of the coarse beds is often blue-grey when freshly cut; but the prevailing tint is a dirty greenish-grey. In many places, where the alternate beds are not to be traced, the deposit seems to be a mixture of both, having a fine grain and a greenish-grey tint. The granular pepper-and- salt aspect of the coarsA* beds is very peculiar, and in its frequent conjunction with the fine-grained slate or shale enables us to trace and identify the rock in various localities. The softer beds underlie great part of Penzance, and extend on the shore as far west as the Wherry Rocks ; and inland, the dull greenish-grey variety and the glossy shale were both visible in the town-cuttings on York Hill. It is, I think, indisputable that these coarse and fine-grained beds are due either to separate depositions by water, or to mere settlement in water. A piece of dried mud which I took from a pool in the Hayle quarry showed the coarse grain and greenish colour at the bottom, and the fine grain and greyish colour at the top.* This undeniably sedimentary rock supplies me • I cannot identify this formation with any of the definitions of I^^* Forbes or Dr. Boasb. No doubt its laminated fine-grained beds might ^ called clay-slate ; but that term could not be applied to the whole deposit. in the Land's End District. 5 with the first Unk in the chain of transition. I am prepared to show, 1st, That its softer beds, which we may call clay-slate, pass into hard quartzose clay- slate, and more rarely into purple killas and into greenstone; that its glossy shale passes into purple killas ; that its intermediate variety also passes into purple killas; and that its coarser beds pass, either by a mixture of actinolite into a sort of greenstone, as at Marazion, or into a hardened felspathic rock closely allied to certain elvan-courses, and to mixed masses of felsparite which border on granite. 2nd, I shall show that elvans and felsparite pass into purple killas on one hand, and into massive fel- spar on the other. 3rd, That purple killas passes into axinitic green- stone and into hornblende rock ; but not, I think, into the coarse felspathic greenstone of the Marazion rocks. 4.th, That links may be found between felspathic greenstone and granite; but not, I think, between axinitic greenstone and granite. As these facts can only be established by long details connected with the examination of numerous specimens, we need not detain the meeting by the several proofs, but proceed to notice the manner in which these transitions have been effected, and the forces which may have been instrumental in pro- ducing them. (i) Transition in structure. (ii) Transition in substance. (iii). Connection if not transition shown by alter- nate courses or beds. 6 On Transition and Metamorphosis of Rocks (iv) A union of complete transition and sharp separation. (i) Transitions in structure. There are schistose forms of granitic and hornblendic rocks, so too there is a schistose as well as a compact form of oui' own purple killas. This being so, there seems no reason why the laminated Lelant rock as it becomes purple killas in substance should not become schistose purple killas in structure ; but as a rule it does not : its tendency is to become a tough compact purple killas, which does not break readily in the direction of the surface planes. Further, there seems no reason why schistose purple killas, as it becomes more hornblendic or feldspathic in composition, should not retain its slaty structure, and' become hornblende slate or gneiss; but as a fact it does not: it becomes more massive in structure, as its substance is pervaded by hornblende or felspar. All changes in the composition of rocks seem to be accompanied in this district by a change in structure from the schistose to the massive. Further, transition is sometimes implied by iden- tity of structure amidst change of substance. It is curious to see in the 6t. Ives cliffs how completely the weathering and general aspect of the Lelant rock are preserved, when the hammer reveals the substance of the purple killas. In many places the surface is honeycombed and disintegrated in a man- ner which does not belong to ordinary purple killas, but which does belong to the softer Lelant rock. I do not know how to explain this, except by the sup- in the Land's End District. 7 position that the Lelant rock has really became purple killas. In the same way the purple killas at Mouse- hole, at its junction with the granite, so retains its external aspect and its dark weathering that e?en an uninstructed eye can in many places trace the sharp line of junction, while the hammer shows that fel- spar is largely mingled with the killas, oftenest in the plains of lamination, producing spotted purple killas, but sometimes destroying the schistose struc- ture and forming massive felsparite. We can hardly doubt that this mixed rock, which still retains the external aspect of the killas, has been subsequently modified and become felsparite. (ii) Next as to transition in substance. Its most complete form is that in which the very substance of two different rocks may be seen interpenetrating each other, even in a hand specimen. Clay -slate and purple killas at the Wherry rocks — Lelant rock and purple killas in the St. Ives cliffs — felsparite and purple killas at Polmenor and Newlyn — greenstone and purple killas everywhere, meet in this particular mode. It does not in itself prove that the one rock becomes another, for it may result equally from a mixture of original elements, or from two separate masses having been forced together while in a soft pasty state. Another form is, when two rocks are so inter- mingled that the substance of one retains the grain of the other, as the purple killas at Carrickgladden Point retains the glossy grain of the Lelant shale. In this case the shale has manifestly become purple killas. 8 On Transition and Metamorphosis of Rocks Another form is when one substance pervades another through a series of minute cross -joints. . Nothing is more common than to see actinolite thus invading purple killas; so that in a hand-specimen, whilst the fractures in one direction show the grain of the purple killas, every fracture in the other direction reveals the actinolite. In both this and the former case some law of crystallization seems evident, which acts across the grain of the original rock, instead of penetrating through it as the easiest entrance. It is a more doubtful case of transition when iso- lated veins or bunches of one substance are found in another. In a hand-specimen we may find a spot of purple killas, or of something like greenstone in the very centre of a piece of Lelant rock ; or bunches of actinolite beginning and ending in a bit of purple killas. And we are told that the same thing hap- pens on the large scale, and that masses of granite are found completely isolated in slate.* These facts are not perplexing if both rocks are assumed to be of contemporaneous origin, but it is hard to understand how a solitary piece of rock could be metamorphosed and reformed while all its surround- ings remained unchanged. Doubtless, if isolated decomposition begins, isolated reformation may follow it; nevertheless, I think we must admit that this class of facts is more in harmony with a theory of original chemical affinities than with that of subse- quent metamorphic action. • Oeol. Ttans, of Cornwall, vol. v. p. 167 ; Fritn, Oeol., p. 144. D^^. in the Land's End District. 9 (iii) Connection, if not transition, is manifested in alternate courses and beds of rock. By courses I mean bands of rock divided by joints more or less vertical, and which in this neighbourhood, according to my experience, run from N.W. or N.N.W. to S.E. or S.S.E. An instance of the alternation of soft and hard courses occurred lately in the cutting for the new St. Just road near Tregavara Lane. At the northern extremity of the cutting there was a mass of hardened purple killas mixed with actinolite, then came a block of white axinitic rock allied to green- stone, then rotten ground, then a band of white rock much decomposed, then rotten ground, then a band of greenstone much decomposed and blackened, then rotten ground, then another black band, then a long piece of rotten ground, then a quartz vein, and on the other side of it lamellar clay slate, or purple killas. The same alternation of hard and soft courses was shown in the cutting at Leskinnack Gate. These facts remind us of the alleged alternations between granite and slate, and seem to imply some law of structure at present unknown. Of alternation in beds, the Gurnard's Head is an admirable instance. The plate which accompanies Dr. Forbes' account of that promontory * gives little idea of the twelve or fifteen narrow beds of schistose purple killas which regularly cap the upright masses and shattered terraces of more crystalline rock. And the terminal mass, which is marked hornblende rock in the plate, is itself built up by beds of greenstone ♦ Oeol. Trans, of Cornwall, vol. ii. 10 On Transition and Metamorphosis of Rocks with intervening stripes of purple killas. That ter- minal mass is held by some theorists to be a bed or series of beds of submarine lava intermingled with the stratified mud of the sea-bottom ; and a vein of so-called hornstone is triumphantly claimed as a proof of collision between igneous and aqueous forces. As a matter of fact, there are perhaps twenty places where beds of greenstone and purple killas come in contact, and there are but two or three where this hornstone is found; moreover, it is found with purple killas above as well as below, and with green- stone below as well as above, though sometimes it runs on a line of well-marked contact between the two rocks. The so-called hornstone I believe to be nothing but a vein of massive and somewhat impure exinite, a mineral very common in all our western greenstone. The union of these two rocks, I hold to be, not accidental, as by the intrusion of lava, but structural ; that is to say, it is part of the structure of the whole mass, the beds of crystalline greenstone and the beds of schistose killas that cap them being as much one rock as the fine mud of an estuary and the coarse sand beneath it are one aqueous deposit, as the scoriaceous surface bed and the basalt pillars beneath it, are one lava stream. In confirmation of this I would point out the regularity of the alter- nation on the western side of the Head, also the identity of structure which runs through the whole promontory, the tilted edges of the beds dipping harmoniously N.N.W., while all the surface planes dip towards the north-east. We can find hard horn- in the Land's End District. 11 blende rock on the western faces of the terminal back-bone and head, and well-marked layers of purple killas between them ; but if we go round the northern side, and climb down the eastern descent, the whole mass becomes more schistose, and the two rocks are mixed together in shallow irregular layers. The whole mass is plainly under the same law of structure; but on the west we have the uptilted edges of the deeper beds, where structure is best developed, and on the east we have the surface planes, where structure is worst developed. Whether this common structure is one of original formation or of subsequent metamorphosis is another question ; but all facts on both sides should be fairly stated. On one hand, I was certainly surprised to find 'on the great bed of purple killas which under- lies the grassy slope of the promontory, weather- stains and eroded surfaces, and white lines of deposi- tion, which much resembled those of the Lelant rock. Moreover, these white lines certainly do be- come harder in the more compact purple killas, and seem to point onwards to other and more crystalline white lines near the hornblende rocks, and finally to the so-called hornstone or axinitic veins. On the other hand, the very substance of the purple killas is often so intimately but confusedly mingled with that of the greenstone as to forbid the idea that the one could have been metamorphosed while the other remained unchanged. And this brings me to my fourth division. (iv) Gradual transition is in some rocks united with 12 On Transition and Metamorphosis of Rocks sharp separatioD. For instance, if clear division and alternation between purple killas and greenstone is so frequent at the Gurnard's Head, gradual transition and complete intermixture are also frequent there, proving that if there be a regular structural connec- tion between the two rocks, it is a regularity very easily disturbed. The same thing was evident in the little quarry lately opened opposite Alverton Gate, from which I have a series of specimens, showing both a gradual transition and sharp separation. It resembled the Gurnard s Head also in its prevalent joints and courses, running N.N.W. and S.S.E. It had, moreover, a partial alternation of the two rocks cut oflf by the occurrence of the joints. And in the fresh fractures of the quarried blocks the wavy lines and smooth greasy texture of the killas appeared confusedly mixed together with a coarse-grained mixture of axinite and actinolite, as though there had been an imperfect mixture of original materials, the large grain of the latter rocks wanting the pasty matter of the killas to form our usual compact homogeneous greenstone. The same union of gradual transition and sharp separation may be seen in the mixed felsparite and killas of the sea rocks between Newlyn and Mouse- hole. Every shade of gradual transition is there, and yet in a hand-specimen they will be sometimes sharply separated. There are no regular beds or courses of rock, no systematic tendency anywhere towards transition, but felsparite and killas, and in- termediate varieties, are all mixed together in stripes in the Land's End District. 13 and patches and shapeless blocks in the most com- plete confusion. The same union of gradual transition and sharp separation is found in the junctions of granite and killas; in one place gradual transition, in another sharp separation, but in either case there is a certain relation between the two rocks. Dr. Boase distinctly tells us, that not only in Cornwall, but throughout great part of Europe, any special characteristic of a mass of granite is shared by the rocks around it.* In al) these instances we have the relation and transition which belong to laws and affinities, and also the confused irregular mixture produced by the rough action of mechanical forces. As to the nature of these forces, I venture briefly to suggest my own conviction, that the force which elevated the rocks of this district was not simply ele- vatory but undulatory, and that it acted as the ocean acts on a line of cliffs, not by a dead weight of water, but by the impetus of a million successive waves. Even now earthquakes are known to act in undula- tions, and we speak of an * earthquake wave * as familiarly as of an ocean wave. , An undulatory force would have two effects: it would produce a stretching out or rolling of beds so far as there was any room for free action in a hori- zontal direction ; and it would produce lines of ten- sion and fracture at right angles to its course. We t see both these effects in our bay in a storm ; the un- c dulations come rolling in from the Atlantic, produc- ^_ ♦ Primary Oeohgy p. 206-8. / 14 On Transition and Metamorphosis of Bocks ing lines of breakers at right angles to their course, and stretching out sheets of foaming water on the surface of the sea. So, if we look at a geological map of our own county, we see lines of greenstone and elvan running S.W. and N.E., whilst the quarry courses of which I have already spoken run at right angles from N.W. to S.E., in strict conformity with the lines of our western valleys, which, as Mr. Whitley has shown us,* generally follow this direction. So also the horizontal joints and beds of surface granite, the occasional schistose structure of greenstone, the lamination of purple killas, and the apparent stretch- ing of the spotted purple killas, might all be due to a lateral motion imparted by an undulatory force -to a pasty mass. The occasional prevalence of the undulatory over the elevatory force might also explain why various kinds of unstratified rocks have (to use Phillips's phrase) " their stratified analogues " in some districts and not in others. If the constituents of granite or greenstone were rolled out instead of being allowed to settle and coalesce under steady pressure, it is very possible that they would take the forms of gneiss and hornblende slate. Another force, that of gravitation, manifests itself in aqueous deposits by separating and settling the liner and coarser particles. In connection with this we must remember Mr. Scrope's opinion (now re- ceived by many), that if lava be under pressure which forbids the formation of steam, it may be loaded with ♦ Geol. Trans, of Cornwall, vol. vii. p. 360. in the Land's End District. 15 water, and be in the state of red-hot mud. The question then occurs whether the force of gravita- tion (acting conjointly with chemical affinities as the whole mass cooled and set) might not cause a settle- ment of the fiery mud, tending to produce an alter- nation of fine and coarse-grained beds when the pro- cess was undisturbed, and an irregular mixture of fine and coarse materials if the unquiet fire-sea was agitated. The union of chemical and mechanical forces gives a wider variety of result. Take, for instance, that curious law by virtue of which crystallization comes into play at right' angles to surface planes. The most familiar illustration of this is found in basalt. In a horizontal stream of basalt, the crystals, or as we commonly call them, the pillars, are perpendicu- lar, but in a vertical dyke of basalt the crystals are horizontal. Are there not glimmerings of the exist- ence of some such law in the transitions which occur among our primary rocks? Purple killas forms across the grain of the glossy shale; actinolite and horn- blende creep in through minute veins in cross direc- tions to the grain of the purple killas; and so perhaps, on the large scale, the forces which have produced alternate hard and soft courses, have come into play on N.W. and S.E. lines at right angles to tlie direction of the bands of greenstone. Chemical affinities also have doubtless a powerful influence in effecting transitions. The great differ- ence between granitic and hornblendic rocks is, first, a larger proportion of silica and alumina in the 16 On Transition and Metamorphosis of Bocks granite; but, secondly, the presence of potash or soda in granite, and of lime, magnesia, and oxides of iron and manganese in hornblende. Now, these minerals — potash, soda, lime, magnesia, and the pro- toxides of iron and manganese — are isomorphous; alumina and peroxide of iron are isomorphous ; that is, they have " the power of replacing each other with- out producing any noticeable change of form in the crystal of the mineral."* It appears, then, that one great difference between felspathic and hornblendic rocks consists in the presence of minerals which have special facility in replacing each other. Naturally this would seem a fruitful source of transition in rocks. Greenstone itself is an illustration of this. It is said to be a mixture of felspar and hornblende ; but in Durocher s analyses given by Jukes,t the green- stone has less potash than the felspar would have supplied, less magnesia than the hornblende would have supplied ; but it has a large excess of the oxides of iron and manganese. The latter minerals seem to have replaced the former. So with regard to the axinite which abounds in our western greenstone. It seems as if part of the alumina which would have formed the felspar had united with some lime and oxides of iron and manganese supplied by the horn- blende, and so had formed massive axinite in the place of felspar. This facility of replacement pro- bably explains why hornblende so readily penetrates and absorbs crystals of felspar, as it does in the * Jukes' Manual of Geology ^ p. 24. t Manual of Geology y p. 75. in the Land's End District. 17 Round Rock and the Wolf Rock; indeed felspar crystals appear to me in a very unstable condition, peculiarly liable to be invaded and absorbed by other minerals — by oxide often, as we all know, and here by hornblende and by chlorite, as I have noticed in vein stones in the Liskeard district; they also gradu* ally disappear in the massive felspar Polmenor elyan- stone. The metamorphic theory assumes that tliere is a reconstructive action continually tending to- wards granite as a final form ; but the foregoing facts incline me to doubt whether hornblende is not the stronger and more permanent form of the two. To conclude; many of the facts connected with transition amply prove the existence of metamorphism; in other words, that some rocks actually change into other rocks; nevertheless I have not been able to discover any trace of a regular order or system of metamorphism. That granite is brought by degrada- tion to the state of sand and mud, that these are changed by heat and pressure into sandstone and slate, and then by further heat and pressure restored to the state of quartz, rock, and granite, is a theory far too narrow to include all the facts of our own limited districts. Several objections occur. In the first place, how are we to account for the fact that the very same rocks which sometimes pass into each other by gradual transition, are at other times sharply separated ? Thus near Porthminster Point the Lelant rock lies upon, and is clearly separated from, the purple killas by a series of quartz veins. Thus in many places the granite is sharply distinct from the VOL. IX. c 18 On Transition and Metamorphosis of Rocks killas. It is hard to account for this by any theory of metamorphosis. Again, the confused irregular intermixture which sometimes takes place between two rocks, as between felsparite and purple killas, and purple killas and greenstone, makes it difficult to believe that the one has been altered while the other remains unchanged. Again, there are the narrow limits to which transi- tion is sometimes confined. When granite and killas meet, though the general disturbance of one or both may extend far beyond a few feet, it is no less true that often, within a few feet of the junction, perfect specimens of each rock may be found. Now, when we consider the strength of the forces necessary to manufacture miles of granite out of killas, it is but reasonable to suppose that they would have at least partially altered a wide tract of intervening rock. It is difficult to conceive how they could have failed to do this, if they were forces potent enough to trans- form one rock into such huge masses of the other. Again, there is the strong argument derived from change of structure. As I have noticed before, the transitions in the substance of our rocks are accom- panied by transitions in structure — internally from the laminated to the crystalline, externally from the schistose to the massive. Slow heat under pressure is known to produce these changes ; and as slow heat under pressure is the chief agent invoked by the theory of metamorphism, we have some right to con- clude that the laminated structure would be destroyed in the process of transition; yet hornblende slate in the Land's End District. 19 and gneiss are well-known forms, highly laminated, and said to be highly metaraorphic. Again, it must be remembered, that the fact of transition is in itself no proof of systematic meta- morphism, since it belongs equally to rocks that must have had diflTerent origins. The hmestone of Glen Tilt* becomes silicious at its junction with granite, but no one thence argues that it is the ultimate des^ tiny of limestone to become granite, or that granite once was limestone. In short, the whole result of my investigations pre- sents a singular anomaly between theory and facts. According to facts, it is comparatively easy to estab- lish a series of transitions between the sedimentary felspathic Lelant rock and greenstone; but not so easy to establish such a series between that rock and granite — elvan-courses being the principal link. Ac- cording to the theory of metamorphism, the case should have been reversed. The felspathic sedi- mentary rock should have passed onward readily into crystalline granite, and only have tended towards greenstone by the side introduction of hornblende. At present I can only regard granite as a somewhat isolated rock, connected with others by chemical aflBnity rather than by manifest transition. Perhaps the felstone of Ireland, and the hornblendic granite of Scotland, may supply links in transition which are wanting in Cornwall. The introduction of hornblende and other minerals forms another objection to the theory of metamor- phism. Where do its lime, iron, and magnesia come so On Transition and Metamorphosis of Rocks from? They at least are simple elements, which must have had some origin independent of metamor- phism. Again, where does the alkali of our granite and its surrounding kijlas come from? Dr. Boase has already pointed out that it is not found in later deposits.* Again, where do the metals of our mineral veins come from ? Eitlier they are a new intrcJduc- tion, or they existed in former sedimentary rocks as the waste of still earlier metallic deposits. But, in that case, would they not have taken the form of horizontal beds, like our own stream -tin and the iron-stone of the coal fields? If all these new ele- ments have existed outside of the assumed circle of metamorphic action, independent formations may have arisen, and be still arising, outside of that circle also. Metamorphic and igneous action are but the result of forces acting upon existing rocks — of forces which, acting upon free, simple elements, might as aasiiy form original rocks. On the other hand, it appears to me that the theory of igneous eruption as applied to granite and green- stone is utterly untenable, and for this broad reason, that the further we go in our investigations the more insight we get into the existence of relations between these rocks and those which immediately surround them ; whereas eruption is a thing of haphazard, which can have no relation to the point at which it issues. No theory of eruption will explain why our granite is always surrounded by a band of purple killas ; why one so-called rock of eruption (granite) is * Primary Geology y p. 319. in the Land's End District. 21 in bulky masses, and another (greenstone) in narrow wedges ; and why one so rarely comes in contact with the other. If, indeed, our granite and greenstone were in any sense eruptive, that is to say, if they were pushed in a plastic state into contact with the deposits around them, I submit that it was done und6r such circumstances, and in conjunction with such unknown forces, as to make the analogy with modern eruption a point not worth mentioning, nay, tending rather to mislead than otherwise. When we refer the original or metamorphic opera- tions of nature to vast depths beneath earth or sea, where pressure forbids the formation of steam, where water and mud may become red-hot, and where white-heat reverses (as we are told it does) many of the laws that act upon the earth's surface, we deprive ourselves of all excuse for confident speculation or dogmatic assertion. In that unknown sphere there must be room for all the agencies to which every theory has appealed — aqueous, igneous, chemical, electrical, mechanical — sometimes one prevailing over the rest, sometimes all inseparably mixed together. A CONTRIBUTION TO THE THEORY OF MINERAL VEINS. Bt Robert Hunt, f.r.s. Two constants appear to have been established in relation to the phenomena of metalliferous deposits; one is the uniformity of main general direction of the productive lodes, and the other is the influence of the proximity of dissimilar rocks. It is very desirable that every possible information upon these points should be collected and recorded, as such a record would serve to establish upon yet more certain data the universality or otherwise of these positions. Two hypotheses, or perhaps three, appear to pre- vail as to the origin of metalliferous veins. One, and that is the least generally adopted, is, that they have a purely igneous origin; that their contents indeed have been sublimed from great depths, and condensed against the sides of the vast fissures through which the vapours made their escape from the profound depths at which they were formed. Another view is, that the fissures now forming mineral veins were the vents through which thermal waters, highly charged with mineral matter, , were forced to the surface ; that from these hot springs there were The Theory of Mineral Veins. 23 deposited, layer after layer, against the colder sides of the cracks the metalliferous and earthy matters which they held in solution. According to Mr. John Arthur Phillips, this condition can be actually ob- served going on in some parts of California. Highly silicious waters are forced through rents in the rocks, in which they deposit their silica, usually in the gela- tinous condition; and in this soft silica are found particles of iron pyrites, and even gold. The other view supposes waters to have penetrated from above, and that in passing through the rock fissures, which were the natural channels of aqueous circulation, these waters deposited, under the influence of what Sir Henry De La Beche called " rock-conditions," and which Mr. Robert Were Fox and M. Becquerel referred to electrical action, their metallic and earthy salts, forming the lodes as we find them. Admitting that my leaning is towards the latter hypothesis, seeing that the repetition of some of Mr. R. W. Fox s experiments fully confirmed the results obtained by him, I do not desire at present to advocate either one or the other of these views. I only desire on the present occasion to support the view that fissures, whether the natural joints of the rocks or rents sub- sequently formed (it signifies not), were originally formed, and that in those, under one or other of the Conditions named, there circulated fluid matter hold- ing the metalliferous or earthy minerals in chemical Suspension. Presuming this to be granted, I will l]3ention a few experiments which go to show that, without calling in the aid of electricity, there exists 24 The Theory of Mineral Veins a power capable of producing all the phenomena observed. I would have it distinctly understood that I believe electrical energy to be a directing power regulating the place of deposit, but that we are gathering evidence of a vast power common to all matter, capable of producing all the phenomena of mineral lodes. Capillary attraction has been long known. Exosmose and endosmose action has been made tolerably familiar to us. The influences of cellular bodies in condensing fluids within them, and the absorbent powers of porous masses, such as spongy platinum, charcoal, and the like, have been repeatedly shown. It is only lately, however, that we have become acquainted with the facts, that a certain thickness of silicious sand will separate salt from its solution in water, and that agricultural soil deprives the water percolating through it of the or- ganic matter dissolved in it. M. Edmond Becquerel has lately shown, that if two plates of glass are so arranged (by touching at one end, and being kept slightly open at the other) so as to show the capillary curve of attraction, and if between these plates we pour a solution of some mineral salt in water, that the surface force will separate the metal from its chemical combination, and attract it to the surface of the glass, on which it will be deposited as a metallic film. Acting upon this, I have made a few experi- ments, feeling that if we could produce a state of unstable equilibrium in the chemical solution, this metalliferous deposit might take place on surfaces widely separated. By adding to a solution of cyanide The Theory of Mineral Veins. 26 « of silver a very small quantity of an hyposulphite, quite insufficient to produce a precipitation, the sur- face action of the sides of a pint bottle was sufficient to produce this deposition in the form of a coat of sulphite of silver. Aldehyde and grape sugar have a similar power. With porous vessels, this condition can be most readily established, and most beautifully so by the action of charcoal. By putting a piece of freshlyTburnt charcoal into a solution of nitrate of silver, we obtain in a little time very beautiful crystals of silver, and this, be it remembered, is entirely due to the influence of the surface force distributed over the molecules of carbon, arranged to form the cells of the carbonized wood. Experiments are yet required to determine the extent to which this surface force is brought into action. But when we see the manner in which small cracks get filled in with metallic matter, such as copper and silver, and when we meditate on the power with which crystallyanic force is exerted as a mechanical power opening the crack, we can, I think, see that we have opened a door through which we may learn something of the secrets of nature's oper- ations in '^ the dark unfathomed caves of ocean " and of earth. VOL. IX. TOOTH AND FRAGMENTS OF BONES OF HIPPOPOTAMUS, ntOM THB VXI6HB0UBH00B OF OOirSIAimirE IN ALOBBIA. Bt Chablss Fox, The lofty isolated rock in horizontal layers -on which the city of Gonstantine is built, at a height of S,000 feet above the sea, appears to be cretaceous, judging from the inoceramic and other shells in it. It is half encircled by the river Roummel, which has worn or formed a vertical cleft 600 feet deep, or has cut its way in one or two places through the rock, leaving a vast natural arch. Professor Studeler led me to the other side of the ravine and up the ascent of the Mansourah hill, of which the marl rests in almost vertical beds on the limestone. The marl is traversed by thin upright veins of limestone, in which M. Renan, of Marseilles, found teeth of fishes. Walking for some furlongs along the plateau (which has an almost uniform slope to the S.E.), we reached some quarries in the friable sandstone, which does not seem to have a thickness anywhere of more than 50 feet. We soon found, at a few feet beneath the surface, some of the hippo- potamus bones (now presented), and parts of the Tooth and Bones of Hippopotamus. 27 carapace of an Emys probably. The large tooth was ibund in the same quarry : it has suflfered much from the disintegration of its substance, except at its jlearly-defined summit. An entire head of the ani- mal was found in the same plain, which has not in the least the character of a mountain-basin, as its present conformation seems to have little, if any, reference to the hills distant about five miles. The water " tortoise " found in the sandstone, and fossil paludina, and impressions of reeds (or grasses), which [ observed in a water-worn calcareous deposit about 100 yards off, indicate the presence of water formerly, where it could not now lie except in the shallowest pools. The bed of the Roummel river is 800 or 900 feet below the plain. Pudding-stone rests in horizontal beds of marl, where the river leaps out from its rocky prison, and forms a high hill on the west of the city. Gypsum is worked there ; and a salt-spring is probably due to the vicinity of rock-salt. In the interior there are numerous salt lakes, some of them six times as salt as the sea. The French soldiers wade into one, to obtain fresh water from a spring in its midst. Like the great fountain in the harbour of Spezzia, lofty rocks of Salt (noticed by Herodotus), and the salt lagoons, as ^ell as foraminifera, in mountain masses, show that the ocean once covered this boundless desert. The cretaceous system is largely developed in Algeria. It is of a dark colour in the northern, and urbite in the southern districts towards the Sahara. D 2 28 Tooth and Bones of Hippopotamus. MM. Cognan and Nicaisi, geologists of the Imperial School of Mines in Algeria, have described aboat 600 new species of shells in the green-sand; not green, however, there. The Jurassic beds (including the lias in which reptiles have not yet been found) are very extensive. In Mount Aures they are in parts horizontal, in others vertical, as if tilted up through cretaceous rocks. M. Nicaisi has found bones of unknown Saurians (as he thinks) in the green-sand of that mountain near the surface. Nummulite beds, turned up on their edges, form the highest crests of the Jebel Jujura range (at some points 6,000 feet above the sea), and encircling much of the Eabyle highlands, in which mica schist abounds. Miocene beds exist in the fertile Metidjah plain, which lies between the isolated group of the Sabiel hills and the lesser Atlas. Lava has pierced through, or has flowed between the beds, or lifted them up into two anticlinal lines. Columnar basalt, trachyte, and other varieties of lava, appear at diflerent places in the whole region. There are many deposits of gypsum, generally associated with volcanic action. Beautiful specimens of a variety of it, called onyx, were in the Paris exhibition. At Cape Matafeo, the east promontory of the ha; of Algiers, there is a thin bed of lignite near serpen- tine. Some specimens of the latter rock at Delhys, also on the coast, but further east, mai. coal, which seemed to me to be bituminous. As the Tooth and Bones of Hippopotamw. 99 steamer touched there at night, I could not visit the scene of this anomalous combination. The only trace of Devonian rock yet found is a silicified ferruginous stone (not water-worn), which was picked up a by traveller returning from an un- successful attempt to reach Timbuctoo. I could distinguish in it numerous small Spirifera. I present a specimen of a deposit of 80 or 100 feet in height, bordering the Metidjah plain, to which M. Flower called my attention. He considers it to have been a sea-beach when the Sahiel was an island. The city of Algiers is built on the steep N.E. slopes of the Sahiel, and rests on alternating beds of mica schist and gneiss, which rise at Nowzeriah to the height of 1,000 feet. On the N.N.E. there is a large mass of limestone, extending from the sea to a considerable height; at the point de Pescade, especi- ally, it seems to have been affected by igneous action. Enormous rocks are quarried from it to extend the breakwater of the harbour. A small cave has lately been discovered in this limestone about 80 feet above the sea. I saw in it traces of human occupation, traces (supposed by the geologists present) like those of fire, and a layer of gravel, like that of the neigh- bouring beach, which might have been brought to make a dry and smooth floor. There were no human bones, but many of different ruminantia, and two small pieces of flint, probably fashioned by man. Neither in the Sahiel nor in any other part of Algeria, nor in the collection of the " Ecole des Mines," could I find true granite, except in fragments of Roman 30 Tooth and Bones of Hippopotamus. sculpture ; but syenite is in North Africa often called granite. Some fragments only of porphyry have been found in the bed of the river Chehf, near Miliana. In the western division of the Sahiel, thick beds of argillaceous marl rise to the height of 600 feet, where I found terebratula. Dr. Boujot kindly conveyed me to Douera, where in the same formation we found Arcce, PectenSj OstrecSf Dentalia, Corals, &c. It was very hot at the time (5th of March), and Dr. Boujot feared lest I should suflFer from fever-miasma, which in a previous visit of two hours only had made him seriously ill, and would not allow me to linger to collect many specimens, or I should not present the Geological Society with so meagre a sample of them. These clay beds, from their wide distribution, are at present great obstacles in the way of agriculturists. Abutting against the gneiss and mica schist of the Sahiel are horizontal tertiary, probably pliocene, beds, forming a beautiful yellowish freestone, abounding in fossils, of which I beg to present a few specimens. I understood from my friend M. Flower, that he found 70 new species. I hope that he will favour the public with a memoir on these interesting formations. The French geologists have not yet completed their map of Algeria, the result of laborious and ex- tensive observations in that vast region, which presents a very inviting field to our English geologists, who v^ould receive a most courteous and cordial welcome from their very able French fellow-labourers in science. Novmher, 1868. ON IE FOSSIL FISH OF CORNWALL. By Charles W. Peach, a.l.8., OorrMpondtng Member fnf Boyal Oeolofficoi Society t(f OomvmlL 1841, and at several meetings of your Society up 1849, papers of mine were read on the above ject. These were afterwards printed in your nsactionSj and some illustrated with plates. Speci* Qs also were deposited in your museum, and ecially those of which figures were given. In the »ers will be found the localities where they were , and all the particulars then known about them. s to those stated to be fishes I now allude. I may ntion that the late Professor Forbes and others y agreed with me in believing that many of these anisms were fish remains. Some years after 1849, ^fessors Sedgwick and McCoy made a geological r in Cornwall, and, as well as inspecting the rnish fossils in your museum and that at Truro, 1 private collections, collected a number also. ose more especially called fish were carefully and jroscopically examined by Professor McCoy and . Carter, and pronounced to be, not fishes^ but 32 The Fossil Fish of Cornwall. spongeSf belonging to the genus steganodictyunij and made into two species So they wei'e considered up to April last, when Mr. E. Wyatt Edgell published in the May number of the Geological Magazine a letter, stating that these so-called sponges were true fishes, and belonged to a species of Pteraspis. Professor Huxley saw one be- longing to Mr. Pengelly from the Cornish rocks, and this he said was also a Pteraspis " of larger size than any previously known." As the same verdict has been given by Messrs. E. Ray Lankester, Salter, Woodward, and others, I feel bound to accept their decision as final. My opinion had never changed; and although I thought that sponges might have lived vvith these ancient fishes, I felt that the specimens described by me were remains of fishes only. On learning this change, I broke open a box of odds and ends, packed in Cornwall in 1849, and which had remained unopened up to that time, when, to my great delight, the first specimen I turned up was a nice but imperfect dorsal-plate of Pteraspis. It is 6-J- inches in length, beautifully marked with delicate waved lines, and under these in places tubercles, and below all a reticulated net- work. This net- work- like structure deceived Professor McCoy and others, and made them so stoutly stand out against the Piscine character of these really (at that time) ill- understood remains. This net-work structure, they said, was " not to be found in any recent fish." I have, however, met with it in Osteolepis, &c., in the old red sandstone of Caithness, and in carboniferous The Fossil Fish of Cornwall 38 fishes from the coal-fields of Edinburgh and Lanark- shire. Now, it is to be hoped that all will be settled, and in the beautiful monograph on Pteraspidian fishes, in course of publication by the PalsBontographical Society, they will find their proper place. I might make many remarks on these organisms, and other things connected with them; but from believing that my respected friend Mr. Pengelly, who has worked so long and successfully amongst Cornish and Devonian rocks, will fully enter into the subject, and thus render it unnecessary for me to do so, I shall rest contented with saying that it is a real pleasure to me to find that, though late, my opinion was not a wild speculation after all. Old as I am getting, it would be a joy to me indeed to ramble over Cornubia, and endeavour to help to work out the true history of the rocks : their true history is said to be still wanting. I have enclosed a tracing of my large specimen. 30, Haddington Place, Edinlmrgh, 281h October, 1868, NOTICE OP AN ACCUMULATION OF CARBURETTED HYDROGEN, OR «< FIRE-DAMP/* IN THE DING DONG MINE, SITUATED IN THB PABI8H OF MADBON, ITBAB PBNZANCB. By Samuel Hiogs, Jun., p.g.s. Seeretarjf of the Jto^al Geological Society of Cornwmli, The Ding Dong Mine is perhaps one of the oldest tin raines in the world, as its uninterrupted working can be traced for more than two hundred years, many of the present shareholders having inherited their interest for nearly two centuries.* Perhaps no other Cornish mine can record a similar fact, whilst the peculiar names f given to the different lodes, cross- courses, barrows, &c., too numerous to mention in this paper, might well repay the research of the antiquary, and testify to its extreme antiquity. The sett is entirely in the granite. The nearest approach to the killas is on the south, at Hea-Moor, distant about two miles ; on the east, at Ludgvan, about three and a half miles; on the north, at St. Ives, and on the west, at St. Just, the sea boards, distant respectively six and four miles. * The cost-books in existence record the names of Bolitho for nearly one hundred and fifty years, and of Batten for one hundred years, t Bussa, Malkin, Clukey, Jacobin, Ishmael. An Accumtdation of Carburetted Hydrogen. 35 The gas was detected in the 50-fm. level in the Old Ding Dong part of the mine under the following circumstances : The deeper levels in the Old Ding Dong were abandoned about twenty years ago, when the water rose to the 30 or to the 60 from the surface, the adit level here being 30 fathoms deep ; but shortly before the abandonment of the deeper levels, a com- munication was opened at the 50-fm. level, between Old Ding Dong and Ishmael's Mine, about 1 70 fathoms apart. Some four years ago, owing to the underlay of a rich bunch of tin in an adjoining working, it was deemed desirable to re-open Old Ding Dong, and resume Ishmael. Everything went on well until the 7th August last (Old Ding Dong being in fork to the 70), when, in order to facilitate the draining of the Ishmael part of the 50-fm. level, which is some feet below the level communicating with Old Ding Dong, it was found necessary to put in a syphon, that the water might be conveyed to the Ding Dong engine. Two workmen, Ralph Daniel and James Harry, waded in through the slime and water for that pur- pose. They had not proceeded far when a violent explosion occurred, accompanied by a blue flame, which threw them ofi" their legs, and scalded them severely. A few days after the managing agent, Captain Williams, obtained a second explosion by putting in a candle attached to the end of a long staff*. This was even stronger than the first, although no injury of any kind resulted. After a short interval. Captain Thomas Daniel entered, carrying a naked candle, when a terrific explosion ensued, which nearly 36 An Accumulation of Carhur cited Hydrogen. cost him his life. After this, no one was allovred access to the level until Davy safety-lamps had been procured. With the permission of Mr. Wellington, the purser, I on two occasions, accompanied by Captain Williams and the pitman, went into the level with the safety- lamps. The result of our first exploration proved to a certainty that the explosive gas was nothing more nor less than fire-damp, as the flame in our lamps elongated its entire length, and a bluish light flickered around it. We found no difficulty in breathing, but simply a peculiar sensation around our nostrils. At the farthest point we reached, the back of the level was found to have been worked away, and cleared for about 4 fathoms in length and two in height. Beyond this the level was completely choked. It was evident, however, the backs had been worked, and that they had either been filled with rubbish, or had run to- gether. From the peculiar freshness of the granite here, as well as for a few fathoms back from it, it was clear that although the mine had been full of water for 10 fathoms above, none had lodged here. I would observe that for more than 20 fathoms before arriving at this opening, the level was nearly filled with slioie, and through this we were compelled to creep. Here then a space had been left, and this was filled with the gas — without doubt, carburetted hydrogen. Of this the only apparent source was decayed wood (probably the ancient timber-work of the level), the evolved gases from which naturally lodged in this cavity. An Accumulation of Carburetted Hydrogen. 37 On my second visit we went down with the inten- tion of firing it, but did not succeed. I then entered the end with a naked candle. Still no explosion ensued, and I detected merely the presence of foul air. This level still continues free from the gas, as a communication has been made to Ishmaels shaft, distant from this place about 10 fathoms. I believe the only other record of an accumulation of fire-damp in a Cornish mine appeared in the Arminian Magazine for November, 1791; but unfor- tunately neither date, locality, nor names are given ; neither is the name of the author appended, although it must have caused considerable excitement at the time, as it states that seventeen men were killed by the explosion. Such was its force that it hurled the heavy framework of wood on the top of the shaft some distance, which falling on a cottage entirely destroyed it, killing the poor man who lived in it. For this reference I am indebted to the kindness of Miss E. Carne. My best thanks are due to Mr. Wellington, the purser, and Capt. Williams, the managing agent, for their kindness in furnishing me with much of the information contained in this paper. Nwmfihwy 1868, ON THE OCODKRENOE OF METALLIC ORES WITH GAENET ROCK itotb illt78tratma a sebies of oopper oses from belbtone 00ns0l8. By Warington W. Smith, m.a., f.r.8., f.g.s. At several localities within the counties of Devon and Cornwall, considerable masses of garnet-bearing rock have been observed among the schistose strata where they approach the plane of contact with the granite; and from their proximity to important lodes, or being themselves productive of metallic substances, they have, in a few cases long ago, formed a subject of investigation. Thus the garnet associated with axi- nite, epidote, and other silicate minerals in the rocks at Botallack, have from the commencement of this society attracted the observation of its members. The " tin-floors " at the same mine, in which oxide of tin was disseminated in bands of greenstone and garnetiferous schist, were described by Mr. John Hawkins in the 2nd vol. of the Transactions of the Royal Geological Society of Cornwall. The massive garnet (allochroite) associated with copper and iron pyrites in the remarkable lode of Wheal Maudlin, Metallic Ores with Garnet Rock. 39 tear Lostwithiel, is known to collectors in the astern part of this county; and, a few years ago, workings to some extent were opened at Criggas, l-J- lile south of St. Cohrmb, where, from a kind of ossan having been formed by the action of the tmosphere on a band of crystalline garnets and xinite, and being thus a highly ferruginous sub- tance, it was raised and exported as iron ore. But the most extensive and commercially import- nt display of minerals of this class hitherto ex- plored, is that which trends along the northern side •f Dartmoor in an E.N.E. direction, from the neigh- >ourhood of Sourton to the village of South Zeal, over a ength of nearly seven miles. At several places along .his line, and within a distance of from a few hun- ired feet to 'about a mile of the visible edge of the granite, there have been noticed in the more or less altered killas, which dips away from the crystalline rock, masses of brown and reddish gossan, which have led to the establishment of mining operations. The works have been opened upon courses continu- ously traceable for a mile or two miles, and apparently in two nearly parallel bands, which on the west, at Wheal Forest, are a quarter of a mile asunder, but on the east have diverged so much as to leave a mile between the run of Sticklepath and South Tawton on the north, and that of Ram sleigh or Fursdon &Ianor on the south. Many years ago workings were jarried on at Sticklepath and at Wheal Forest, on Lang- rtone Hill, which proved the presence of copper ores tlong with mimdic, but led to no satisfactory j-esult. 40 Metallic Ores with Garnet Rock. More recently Black Down was explored in a con- tinuous line with Wheal Forest; Fursdon Manor mine, now Cosdon Vale, was systematically opened; and within the past three years, Belstone Consols (on the Sticklepath lode) have been the scene of regular mining adventures. The importance of these deposits is best shown by the fact that the last two mines have sold copper ores to the amount of several thousand pounds in value, with some of the parcels ranging from 12 to 16 per cent. The general occurrence of the minerals at these various points is very analogous, and to avoid pro- lixity, I will confine my description to the last-men- tioned mine, which is now opened to fifty fathoms in depth, and many scores of fathoms in length, and which exhibits some of the peculiarities df this series on the largest scale, although removed by greater distance (above one mile) from the edge of the granite. The surface at the Belstone Consols is slightly undulated cultivated land, and here, as at Bamsleigh, a road-side cutting appears first to liave brought the ferruginous bands to notice; but the long cross-cuts which have been driven in the former mine, and the numerous costeaning pits opened to prove the course of the metalliferous lines, reveal the structure of the mining ground over a large area. In the thirty-fathom level the relations of the lodes are most fully exposed. A vertical shaft (" A ") is sunk between two veins, termed No. 1 and No. 2 lode, which are seventeen fathoms asunder, and course ~ Metallic Ores with Garnet Rock. 41 true E. and W. They consist of bands of garnet rock mostly crystalline, and containing disseminated copper pyrites, iron pyrites, and mispickel, which sometimes coalesce into a pretty solid rib of from one to three inches thick, now and then associated with quartz. The bands dip very regularly to the north, with an underlay of 2 ft. 6 in. to 2 ft. 10 in. to the fathom; and the ground between them consists of an alternation of garnet rock and dark silicious slates in perfectly conformable strata. Towards the north, near No. 1, these beds (especially as seen in the fifty- fathom level) assume more of the character of ordi- nary killas. Southward from No. 2 the cross-cut passes through thirty-seven fathoms of similar alter- nation of garnet rock of greenish yellow and pale brown tints, with sharp silicious schists, and then reaches the north wall of the " main lode " (No. 3), which attains a width, measured horizontally, of no less than sijtteen fathoms. To me this appears nothing else than a powerful bedded mass of garnet rock, with a few planes of stratification more or less dis- tinctly visible, and where sotne of the courses are highly crystalline, with the rhombic - dodecahedrons plainly recognisable, whilst other portions consist of massive garnet or allochroite, or are intermingled with schistose bands of matted pale-green actinolite. This thick band is on the whole softer than what has been regarded as the country, and is specked through- out, but very irregularly, with pyrites, mispickel, and black and grey copper ores, whilst occasionally these metallic sulphides and oxides are accumulated in VOL. IX. E I 4S Metallic Ores with Garnet Rock. strings running sometimes with, but often quite ftgainsty the direction of the stratification. Here and there a little green carbonate of copper appears in some of the reddish and pale-grey beds. The resemblance to a true lode formation is also heightened by occasional ruggy portions, and by heaves which dislocate the orey parts. On the south the cross-cut has been pushed a short distance intd strata of a very similar character to and conformable with those on the north. The entire lode is heaved by a cross-course, on which the above-mentioned cross-cut has been driven to a distance of 9 fathoms south in going west ; and a succession of considerable dislocations in the same direction occurs still further west. Below the 30, and in the back of that level west of the heave, considerable quantities of the black ore are being raised from stopes, mostly in portions of the lode where the chief mass is of a soft somewhat gossany character. Here, then, we have the remarkable feature of a band of 96 feet thick of garnet r6ck succeeded on the north by above 300 feet thick of alternations of that rock with hard schists, and the presence in them of such large quantities of copper ore suggests several questions of no little scientific as well as commercial interest. The whole series forms dis- tinctly a group of conformable strata overlying the granite. But the highly crystalline character of the garnet portions, the bright faces and the sharp edges of the crystals themselves, preclude the idea of their Metallic Ores with Garnet Bock. 43 having been deposited as such by the usual action to which we ascribe sedimentary formations. There are certain mining districts abroad where garnetiferous rock associated with metallic ores, as in Scandinavia, in Mexico, and in the Bannat in Hungary, is presumed with tolerable certainty to be the result of metamorphic action. And in the region before us it would appear that a similar explanation is the most probable, and that these bands, which as simple sediment contained the materials needful for the formation of garnet, actinolite, and axinite must have become definite and crystalline under the in- fluence of the neighbouring granite. This position would appear to be confirmed by the circumstances that it is only near the granite that siich appearances are seen, and that the same effect has here been produced on the lower carboniferous strata which in parts of Cornwall are observed in the Devonian. But how to account for the metallic ores? They occur differently from what we find them to do in lodes not limited within nearly contiguous walls, as if resulting from the filling of a fissure, and it be- comes for this district a highly important question, now in process of solution by Messrs. Martien, York, and Co., to determine whether the ores may be ex- pected in such a repository to occur in sufiicient quantity, and thickly enough grouped, to be re- munerative to adventurers. Has there been, let us enquire, an opening and a filling of the lode-fissures precisely coincident with the course of these unusual beds? It appears to 44 Metallic Ores ivith Garnet Rock. me, from the regularity of the strata as well as a prevalent absence of true lode-structure, to be very improbable.'^ Or, may we conclude that the ores were deposited along with the original sediment of the strata ? Such a hypothesis, looking at the history of the occurrence of the copper ores in our Western counties, and the manner in which they here accom- pany bands only of a particular mineral character, would seem to be just as improbable as the former. It appears as though we could not escape from the admission that the ores iQust at one time have had the opportunity afforded them to select those channels of ground that were in mining parlance " congenial" to them, and that the thicker bands of garnet and actinolite rock were in this respect highly favourable to their deposition. Where so bulky a stratified mass of rock as the so-called main lode has been exposed to the action of the chemical forces which have induced its crystallization, and to the physical violence which has tilted it to a high angle and broken it up with numerous joints and fissures, it is fair to infer that an easy access was afforded to waters laden with metallic combinations which would deposit them as definite minerals. But why, if the whole series of strata were at one time saturated with mineral waters, should the valuable contents be limited to certain bands of rock ? And what probability is there, that * The constancy in the direction of these metalliferous bands is certainly a feature establishing a sort of relationship with the lodes ; and it is signifi- cant that the prolongation westward of these of Wheal Forest will nearly strike upon the cupriferous deposit at Bridestowe, which was described by Gapt. Simmons to the Miners' Association. Metallic Ores toith Garnet Rock. 45 in these latter certain portions may be richer than those hitherto explored? What that in depth the chances of success may be as good or better than at the shallow levels ? These questions follow one upon another as we think over the appearances thus brought to view, and we may assert that no definitive reply can at present be given as derived from experience at other copper mines. It is obvious enough that a little more knowledge of these peculiar phenomena would greatly benefit a whole district ; but such knowledge has to be dearly bought in, the slow opening of shafts and levels with hard ground and quick water, and the object of this brief sketch is to point out that a re- cord of the results of so interesting a series of trials cannot but be of high value to the geologist as well as to the miner. ON SOME FOSSILS FROM MOUNT LFJBANON. Bt Alfred Lloyd Fox. The fossils from mount Lebanon which I have sent to the Eoyal Geological Society of Cornwall were for the most part collected by my companion and myself during our rambles, in the winter of 1867-68, through that portion of the range lying between Jebel el Sunnin to the north and the Litany^ where it cuts its rapid channel through the deep chasm be- tween the height capped by the ruins of the strong old castle of the crusaders, Kulat el Shukif, and the little village of Deirmimas, where we slept, on the opposite precipice. The fossils observed by us chiefly consisted of mollusca; viz., casts of Isocardia, and allied bivalves, and of BuccinidsB and Conidse, and shells of Hippu- rites and of Ostrese, which we found abundant over a large area, but clustering in larger numbers in certain favourite localities. Near half a mile to the north of the village of Shemlan, about 2000 feet above the sea level, about fourteen miles from Beyrout, Radiolites (hippurites) cornu-pastoris, a characteristic fossil of Coquand's angoumian stage of the middle cretaceous series, was very common, also Ostrese. Immediately to the south- east of this village is a hard and compact nummulitic Some Fossils from Mount Lebanon. 47 limestone. We were informed that Turrilites and PholadsB were to be found lower down on the moun- tain, a stage corresponding apparently to the Rhoto- nagian of Goquand, marked by Turrilites costatus, of which I have sent a specimen. Above Shem* Ian and Sook el Ghurb we found compressed speGi*> mens of Buccinidse very common. Above D^Hamdun, near the watershed of the Range, we were struck with the profusion of fine sharp casts of isocardia, whilst in the valley of Muchtara (the head-quarters of the Druses), and under Eulat el Niha, and towards Jezeen, we found casts of large Conidse, which latter we were prevented from taking with U3 in consequence of their weight and the long journey before us. One fossil, a rolled specimen, found some 3000 feet above the sea level near B'Hamdun, bearing a re- markable resemblance to a large carnivorous tooth, or to a noble molar of an old giant of Bashan, caused considerable dispute, until Professors Owen and Tennant gave it a place among the characteristic fossils of the hippurite limestone, and considered it to be a valve of a large hippurite* I wish to make particular mention of the accom- panying good specimens of fossil fishes, for which I am indebted to the kindness and energy of a French gentleman, L. Mazin, of the Jesuit College at Ghazir, to the north of Beyrout; also of those of a good cast of ammonite, buccinum, coral or shell- spawn, &C.J all found by him, I believe, within some miles 6f Ghazir. For a few of the specimens I have to thank an 48 Some Fossils from Mount Lebanon. American gentleman, William Bird, of the American Seminary at Abeih, near Beyrout, whose private col- lection of fossils at Abeih is well worthy the inspec- tion of any geologist visiting the Lebanon. Some of the small shells given by him appear to be casts of Paludina, Limnea, &c., and therefore are of lacustrine and fluviatile origin, showing that a complete change must have taken place at this period of the chalk formation. Did not these fresh-water shells exist in some lake in which were likewise deposited the vegetable matter that afterwards formed the lignite beds, of which I have sent a small specimen ? Such is Coquand*s explanation of the appearance of similar shells and lignite beds in Provence. There these fresh-water shells are traced to the base of the Eocene. Do not those in the Lebanon belong either to the Upper Chalk or to passage-beds between that and the Eocene ? The great diflference that exists between the cre- taceous deposits of England and of the valley of the Seine on the one hand, and those of Provence and Algeria on the other, are well known. Do not the Lebanon beds, distinguished by hippurite limestone and lacustrine deposits, bear great affinity to the latter, and contain many strata of the cretaceous system which are altogether absent in England? We also observed here and there courses of rich iron ore, and a fine elvan-course to the east of the Wady et Teim, south of Rasheiya el Wady, in the anti-Lebanon. In many places, as we rode along, we found fossils lying by our road-side in great profusion. REMARKS ON (WITH A LIST) SOME OF THE ORGANIC REMAINS OF CORNWALL, in the museum of the koyal geologioal sooiett of cornwall. By C. W. Peach, a.l.s., Corresponding Jliember of the Society. HAD great pleasure in the spring of the present ear in accepting the kind invitation of the authorities )f your Institution to assist in arranging some of the bssils in the really elegant and spacious museum ately erected. It has been very gratifying (with one )r two exceptions) to find the whole of the fossils ■ormerly belonging to me, not only there, but, con- jidering the long time — twenty years, or nearly — they aad been in the old museum, with their removal to :he present one, in good condition and preservation, even >o their labels. As well as the above, collections made 3y Messrs. TreflFry, W, M. Tweedy, W. Jory Henwood, Pengelly, Giles, Pattison, &c., were also turned up. From all, the dust and dimness were removed by the industrious ladies, who, with unceasing perseverance, prepared the specimens for arrangement on your jhelves. Unfortunately, at present little or nothing jan be done towards naming the collection correctly : 10 many changes have taken place, and are still going VOL. IX. F 50 Some of the Organic Remains of Cornwall. on, in the nomenclature of fossils, we are compelled to wait. Even the geology of the county is not yet settled. We hope this will soon be done, and that the officers of the Geological Survey will re-examine the county, and set the vexed question of the age, &c., at rest. With this, with the excellent mono- graphs of the Paleeontographical Society, and the use of your specimens by the writers of these mono- graphs, new light will be thrown on all, and your large collection will become, not only a standard of reference to your native rising geologists, but to all interested in the Devonian or old red sandstone of the world. There is still much to be done in the county in the way of research in the field; all has not been discovered. It would not surprise me to hear of fossils being found much nearer to Penzance than Porthalla. With this I forward a list of some of the fossils in the two wall glass-cases; these, with two or three exceptions, were selected out of those collected by me before I left Cornwall, in 1849. The remainder, mostly duplicates (many of these might be exhibited if room could be found), are placed in drawers. A large number of the ^^ Steganodictyum" of McCoy were selected, and are now in the hands of Mr. E. Ray Lankester for description in his Monograph of the Fishes of the Old Red Sandstone. Happily these, said to be spongeSy are fishes again after all. I regret that the list is so imperfect, and roust ask you not to rely too confidently on it as regards Some of the Organic Remains of Cornwall. 51 species, for the reason above given. Many were named twenty-five years ago, all gleaned from various sources scattered here and there, and now probably superseded. However, they may serve as an incen- tive to some one to set all right. I need not make any remark on the Silurian part; this has already been so well done by Sir R. I. Murchison. As regards the " Devonian," I have not attempted to give the divisions; at present these for Cornwall have not been defined. LIST OF THE ORGANISMS. Plantce. The rarity of these is marked. The two specimens in your museum are the only ones I ever knew from Cornish rocks. The one I got at Pol- ruan is small, and marked by me when got. I have since seen thousands in Scottish rocks, and adhere to my first opinion. The other is a fine specimen from Mr. Giles's collection, from near Liskeard. It is much like a not uncommon plant of the old red sandstone of Scotland, where it occurs at times two or three feet in length, and of the same breadth all the length ; it has also the same kind of raised centre, and as well oblique markings, probably from shrinkage. Amorphozoa, now Steganodictyum, is taken from this class. We have only one. It is a very interesting one, and has not been found in any other place than South Devon. Sphceronites tesselatus is a curious and interesting sponge, and is a valuable addition to the Cornish list. Codenteratod. These are found in many localities. r\ 62 Some of the Organic Remains of Cornwall. 9 r generally ill-preserved. It is pleasant to be able to notice one species, a Favosites, at Porthalla. A large undescribed Favosites occurs at Polruan and Fowey; it is far from uncommon. I saw one two feet six inches in length. Portions of specimens (now in your museum) are figured in your report for 1848, page 62, plate iv. figs. 7-9. Pkurodictyum problematicum is abundant, and a '* true Devonian fossil." Echinodermata. Pretty generally distributed through- out the county, more so than any other fossil. On the whole they are in detached pieces. Those from Porthalla are in the same specimen of limestone as the Favosites. (No. 733 of Dr. Boase s collection.) Annelida. The only one at present known occurs in sandstone, with prints of ripple-marks and rain- drops, in Highgate Quarry, St Veep. Was first noticed as Cornish in 1850. (See Report, page 125.) Crustacea. Far from rare, especially at Rose Vale Quarry, near Liskeard. Many of them are rather large. (See the one figured in your Report for 1848, plate iii. figs. 3-5.) Unfortunately few are in a recognisable state of preservation. Polyzoa. Though not numerous, interesting ex- amples, mostly casts, occur at Polruan, Fowey, and Looe. Brachiopoda. The most interesting is Lingula, it being an addition to the Cornish list. Although marked by me with (?) twenty-five years ago, I felt it right to submit it to Mr. Davidson, who kindly complied with my request. A copy of his reply ac- Some of the Organic Eemains of Cornwall. 53 companied this. These must be considered standard specimens. Lin guise have been found in the Devonian of North Devon, and in the carboniferous rocks there. Copy of Mr. Davidson^ s letter to Mr. Hthridge on the Lingular from Cornwall. My dear Mr. Ethridge, — It was only this day that I could spare a moment to examine Mr. Peach's Lingulce. The rock which contains them seems exactly similar to those upper shales which occur at Stoly or Plaistow Mile Quarry, parish of Shirwell, in North Devon, and the species seems identical with that named Lingula mola, by Salter, and which I have considered might be a variety of Lingula squamiformis. See my Devonian Monograph, p. 105, pi. xx. figs. 11, 12. I can make nothing positive of the Pridmouth species, as it is so entirely out of shape ; but it might, perhaps, be either a Lingula or LHscin/i, similar to one which at Stoly contains the Lingulse. (Signed) T. Davidson. Lamellibranchiata. A few specimens of each divi- sion, mostly on the east side of the county. Gasteropoda. Rare and poor in species. Loxonema is found in the same rocks as the fish remains, and with Bellerophon bilobatus (see next class) are interest- ing, showing fishes and marine shells together in the same rock. Nucleobranchiata. At present only two ; one above interesting. Pteropoda. Hitherto confined to North Devon. First mentioned in vol. vi. of your proceedings for 1844, page 184. It occurs in three localities in Cornwall. Cephalopoda. Many interesting specimens in several 54 Some of the Organic Remains of Cornwall. localities. The fragment from Porthalla for the first time. Pisces. Your collection is rich in specimens. I have reason to believe that in genera and species more will turn up than expected. When decided they will have a very important bearing on the geology of the Devonian and old red sandstone. At present, for reasons given, we do not appear to be rich in species. However, we have fifteen out of the eighteen classes noticed by Mr. Ethridge in his paper on " The entire Flora and Fauna of the Old Bed Sandstone and Devonian Rocks of Great Britain," in the Quarterly Journal of the Geological Society of London, December, 1867, page 615, table ii., represented in Cornish rocks. The three wanting are — Bhizopoda, Insecta, and Beptilia. The two last can hardly be expected to turn up. SOj Haddington Place, Edinburgh, 26th October, 1869. ON THE COYERT OF ORGANIC REMAINS IN THE ROCKS OF NELLY'S COVE, NEAR PORTHALU; AXfD OF IE CURIOUS OBGAiaO-LIKE MASSES UK A QUABRY NEAR HAYLE. By C. W. Peach,. A.L.8., corresponding Member of the Society. the 3rd of May last, when looking over in your seum the Boase collection of the rock specimens Cornwall, one of limestone (No. 733), from near thalla, arrested my attention. A slight examina- 1 satisfied me that it was fossiliferous. At my aest the authorities kindly got it partly polished, I then crinoids and corals were clearly shown. The cimen and fossils are much like masses got by me !t of the Van, in St. Austell Bay, now in your seum. From being long of opinion that fossils jht be found between the Narehead and Mounts 1^, this discovery was so interesting that I resolved go to Porthalla, and try to refind the rock Dr. ise took the specimen from. I was to have had 3pany. Unfortunately, the weather was so wet and rmy, I had to go alone. In addition to the pelting 1 — with the exception of one day out of the five — tides did not serve for. beach-ranging. Despite 50 Organic Remains in the Rocks of Nellys Cove. these drawbacks, I tried all possible, both under and on the top of the cliflfe, from Porthalla to beyond the Nare point on one side, and on the other some distance beyond the serpentine rooks. I also made a sUght examination at " Proustock " (Porthoustock). I was not fortunate enough to find the limestone of Dr. Boase. Had I been in possession of the information since received, in all probability better luck would have befallen me, and I should not have stuck so close to the sea-coast. The following extract from a letter from Dr. Boase of the 22nd ult. may be useful should any of the working bees of your society go to Porthalla — " I heard from my friend Henwood of your interesting discovery of organic remains in a specimen of limestone near Porthalla, and have since seen in the papers reports of your researches on this subject. I have read over the part of my communi- cation to the Geological Society of Cornwall, and have tried to recall the matter to memory; but a period of about forty years makes the recollection very unreliable; but as far as I can penetrate the gloom, I think the specimen was broken from a point of rock cropping out of waste ground on the top of the hill on the road from Porthalla to the Lizard.*' I saw this rock across the deep valley on my left hand as I went oa the footpath from St. Keverne to Porthalla, but did not go to it, being assured by several that it was the same kind of rock (serpentine) as that which shows in the cliff on the right of Porthalla Cove. For once — I suppose owing to the wet weather and weariness from cliflf ranging — I did not examine Organic Remains in the Rocks of Nelly s Cove. 57 for myself, a most unusual thing in these matters with me. Thus I lost the prize; however, I hope some one will soon get it. My journey was not alto- gether fruitless; for in Nelly's Cove, between tide marks, in the rocks which show above the sand before reaching the high ridge on which the raised beach rests (as represented by Mr. De la Beche.at page 431, fig. 80, of his Geological Report), I got blackened masses in a dark grey rock; one piece is evidently a portion of an Orthoceras. Similar blackened ones are in the collection in your museum from Fowey, Polruan, &c., and it would be well to compare them. I regret that the specimen is so obscure. With me there is no doubt. I have shown it to one well up in fossil lore, and am fully borne out in my opinion. The other specimens from that locality I say nothing farther about than that many such are found with the organisms in the rocks of Polruan, &c., and they are no doubt portions of mutilated organisms. The cliffs, quartz cairns, rocks, &c., remind me much of those of Goran Haven, the Deadman, and Veryan, &c. I think the quartz at the Nare is a continuation of that at Goran Haven, Caerhayes, and Veryan, and that if very carefully examined will be found to be fossiliferous. QUARRY AT HAYLE. At Miss E. Carnes request, I accompanied that lady and Miss Batten to Hayle for the purpose of examining the rocks there, and in the quarry oppo- site the mineral floors we got several nice pieces of 58 Organic Remains in the Rocks of Nellys Cove. curiously striated rock in situ (evidently not slicken- sides), much like impressions of calamites, so much so that had they turned up in a coal-field, I should have considered them truly so. One specimen I left in your museum ; unfortunately, I did not keep one for myself. I refer to these specimens from having read in the September number of the Geological Magazine^ page 393, the account of " Fossils in Eophyton Sand- stone in Sweden." The paper is illustrated with three plates: in plate xi. fig. 3 is one so like the Hayle specimens, that it would be well to search farther, and if shells (lingulse) also turn up, then probably we shall have the equivalent of the Eophyton sandstone in Cornwall. I saw at the Geological Rooms, when in London in June last, some of the Swedish speci- mens of Eophyton sandstone with the fossils. Not a vestige of organic matter was to be seen. After seeing these and the plates, and having read the paper above alluded to, rest assured if the Swedish specimens art truly organisms^ so are the Hayle ones ; and I hope that you will soon re-discover the Porthalla limestone, and work out the Eophyton (?) riddle too. I forbear any remark on the geology and rocks, dealing only with fossils ; for I fear I have intruded too long already. 5^ NovembWy 1869, SOME OBSERVATIONS ON THE MAGNESITE OF SILESIA. By Lovell Squire, Jun., b.a. f the course of a tour through North Germany in e spring of 1868, the writer spent a week or two 1 the county of Glatz, in the south of Silesia, and mailed himself of the opportunity to examine the lagnesian formations in the vicinity of Frankenstein. s this district is out of the usual track of English avellers, it is thought that a brief account of the 3markable deposits of magnesite which its contains lay not be wholly uninteresting to the Cornwall reological Society, our own county being so rich in 3cks of allied origin. It is right to state that the compiler of the present aper is under obligations to an admirable essay by Ir. Wilhelm Richter, of Breslau, entitled, De eo %od ad Frankenstein invenitur Magnesito, which was indly lent him by the Protestant pastor of Frank- nstein. Native carbonate of magnesium (or magnesite) ccurs in both the crystalline and amorphous state in arious parts of the world; but, so far as we know, it as not been noticed in the British Islands. The morphous variety, of which we have now to speak, is 60 Observations on the Magnesite of Silesia. stated by Richter to exist in the following localities : Frankenstein, in Silesia; Kranbat, in Styria; Strub- schitz, in Moravia ; Greece ; Madras, and Salem, in India ; and on the river Pitsch, in California. Nicol mentions also Yalecas, in Spain; and Dana quotes two or three localities where it is found in the United States. The Jermyn Street Museum, in London, contains a specimen from Turkey. A few days ago the writer had a specimen of serpentine from the Shetland Islands put into his hands by Mr. A. Lloyd Fox, which is partially coated with a white substance, having every appearance of being magnesite; but there is not enough of it to afford a satisfactory analysis. A distinct evolution of gas was observed on treating it with an acid. Magnesite is rarely if ever found perfectly free from an admixture of other substances ; but the Silesian deposits are for the most part sufficiently pure for practical purposes. A recent analysis of a sample from the Frankenstein district is as follows; say in 100 parts by weight- Carbonate of Magnesium . . . 93'00 SiHca . . . ; . .5-60 Alumina 0*85 Carbonate of Calcium . . .0*40 99-85 Rammelsberg says the silica varies from 5 to 8 per cent. ; but in some cases where the magnesite is very gritty and impure, it would doubtless contain much more than this. The carbonate of lime does not seem to average more than J per cent. I Observations on the Magnesite of Silesia. 61 In order to gain some idea of the locality, which s the only available source of magnesite in the North )f Europe, let us imagine ourselves standing among ;he ruins of the old castle of Frankenstein, on the jouthern edge of the vast plain that stretches across Prussia from the Baltic to Bohemia. Level though .he country appears, there is a gradual elevation as it recedes from the coast, and the meadows around us are some 500 feet above the sea. The eastern flank of the Riesen-gebirge (which is in this part a mere assemblage of green hills of no great height tumbled pell-mell together) shuts in the view to the south- west at a distance of about seven English miles; and in the intervening space to the southward of Fran- kenstein, the village of Baumgarten lies concealed among a group of hills, isolated outliers of the mountain-country beyond. It is along the sides of these hills around Baumgarten that the magnesite quarries are chiefly to be found ; and we accordingly turn our steps in that direction. We make our way across the Groch Berg, noticing a few old worked-out quarries on the hither side as we go along; and on arriving at the eastern declivity, signs of operations now in progress become visible. It is a large grass field, and here and there we observe a heap of white stones. On approaching nearer we perceive the cavities from which these have been raised — pits sometimes saucer-shaped, and sometimes (but less frequently) sunk like a well or shaft to a depth of perhaps ten or fifteen feet, with adits in some • instances driven into them from lower down the hill. 62 Observations on the Magnesite of Silesia. The magnesite is hewn out in blocks very much resembling in appearance the Cornish kaolin, known as china stone; and an intelligent young peasant whom we meet with tells us that the farmers eke out their earnings by sending their men and horses, when there is nothing better for them to do, to raise the ** white stone," as they call it, from the fields, and deliver it for a small price to the merchants' yards at Baumgarten and Frankenstein. We enquire how they know where to dig for it, and learn that this primitive kind of mining is carried on (like some other more expensive operations nearer home) very much at bap- hazard. They dig a pit anywhere at random, and if they do not find the mineral they are in quest of, they move on and try somewhere else. They find it generally in what they call "nests," the subjacent rock (which appears to be invariably serpentine) exhibiting after the removal of the magnesite a sub- concave, or, as we have termed it, a " saucer" shape, as if a hollow had been formed in the silicious rock, and then filled up with a deposit of the carbonate. We ask if they do not sometimes try sinking a little deeper; but this seems to be regarded as too Quixotic an enterprise to be thought of; and from the character of the surface-deposits it is probable that they are right in not expecting to be rewarded for the cost of mining. On handling the stone, and trying it with a penknife, we find that it varies considerably in texture and hardness ; and upon enquiry we learn, as we expected, that there is a corresponding difference in the value. Much of it contains a large quantity of Observations on the Magnesite of Silesia. 63 hard silicious matter, and is comparatively worthless; whereas the better qualities, with a minimum of impurity, are similar in consistency to chalk. We pass on to the works more immediately con- tiguous to the village, and here find the quarrying carried on more systematically and continuously, but with no essential difference from what we have already seen. The men engaged in these works (which belong to the magnesite merchants) are not disposed to be communicative, and appear ^jealous of a strangers approach. On both sides of the village of Baumgnrten, along the flanks of the hills, we see at intervals the piles or stacks of white stone, reminding us forcibly of the china clay district around St. Austell. At Baumgarten we pay a visit to the establishment of Mr. Stilbig, who is one of the two or three local men that employ steam-power for pulverising the magnesite, and we obtain permission to enter the mill and see the process. The blocks of stone are first crushed by stamps like those used for crushing ores in Cornwall, and after being thus reduced to small fragments, are ground between millstones to the fineness of flour. We cannot discover that any process of washing away or otherwise separating the silicious particles is adopted; and it is probable that the manufacturers of the powdered magnesite (or dampfrnehl, as it is called) simply rely on a careful selection of the stone to be crushed, the produce of the best quarries being tolerably pure in its native state. There are at Frankenstein, Baumgarten, and Fran- 64 Observations on the Magnesite of Silesia. kenburg about twenty owners of magnesite works, most of them coming under the class of peasant proprietors, and disposing of the stone they raise to the three or four exporting merchants. Germany and France appear to be the principal consumers, magnesite being a very convenient sub- stance from which to obtain the carbonic acid gas employed in the manufacture of champagne and aerated waters. Every practical chemist knows the objections to the use of chalk or any carbonate of lime for the production of carbonic acid. If we treat chalk with a solution of hydro-chloric acid, the volatility of the re-agent causes some of it to come oflf with the carbonic anhydride, and necessitates a tedious subsequent process of purification ; and moreover, the disengagement of the gas is apt to be inconveniently rapid; while, if sulphuric acid be used, the sulphate of lime produced being nearly insoluble, forms a kind of plaster, which hinders the complete decomposition of the chalk. The substitution of magnesite for carbonate of lime obviates all these diflBculties. By treating the former with sulphuric acid, a slow and regular evolution of carbonic acid gas is secured, and the sulphate of magnesia being readily soluble, the whole of the magnesite is decom- posed and utilized, while the residue has a commercial value as Epsom salts. In processes where large quantities of carbonic acid gas are required, it can be obtained from magnesite by simple calcination, as in lime burning, the gas being given oflf at a much lower temperature than from limestone. It is said Observations on the Magnesite of Silesia. 65 hat the facility of its expulsion by heat from a uagnesian carbonate first led to the study of the )roperties of carbonic anhydride. Another use, for vhich magnesite is especially adapted, is the cleansing )f boilers supplied with sulphurous water, the solu- ^ility of the sulphate of magnesia produced prevent- ng incrustations such as result from the employment )f lime. Numerous other applications of a similar character ivill readily suggest themselves, besides the obvious 7alue of the magnesia as a drug, and for the manu- facture of magnesium ; and it is only strange that so valuable a mineral is not better known in this country. A few importations have been made into England for making Epsom salts, and probably for magnesium works, but not, it is believed, to any great extent. So much then for the economic value of magnesite. Let us turn to its geological associations, and see if they will throw any light upon its origin. For this purpose it is needful to cast a glance at the rocks to which it is found in proximity, and especially the old quarries (already cursorily referred to) from whence it has been removed. The hills about Baumgarten consist in great part of greenstone, diallage, and similar rocks, intermingled with quartz and masses of serpentine, and, as has been already mentioned, it is in juxta-position with the latter that the deposits of magnesite occur. It may be worth a passing I'emark, that magnificent specimens of the variety of chalcedony called chrysoprase are found in these bills. The Frankenstein serpentine is peculiar in VOL. IX. G 66 Observations on the Magnesite of Silesia. appearance, being of a dark colour, and the surface very much cracked and apparently weathered. In the smaller hollows or *' nests " from which magnesite has been excavated there is nothing very remarkable in the look of the exposed rock ; but when we meet with a larger surface where we can trace the "joints," as in the nearly perpendicular sides of some of the old quarries, we are forcibly struck with the resem- blance to a wall of masonry, the interstices of the joints being filled with magnesite, just as if the serpentine had been built up in blocks and cemented with mortar. In some places a certain asbestos-like fibrosity of texture may be observed pervading both serpentine and magnesite at their point of junction. The deposits of magnesite seem always to occur either close to the surface of the ground or where there is a direct communication with the surface by fissures of the rocks, and we are thus led to suppose that it is not of Plutonic origin. Its invariable juxta- position to serpentine further shows that it is not a sedimentary aqueous deposit, as in that case we should expect to find it superposed on all the rocks of the district, and not confined to one kind only. There appear to be no indications of an organic origin, and we are driven to the conclusion that it has been produced by chemical action since the adjacent serpentine has been in its present position. Assuming then, as we seem justified in doing, that the magnesite owes its origin to some metamorphic process which has acted upon the serpentine in stdi, it remains to consider what that agency can have Observations on the Magnesite of Silesia, 67 been. The whole question of the metamorphoses of mineral substances is surrounded with so much obscurity, that it is with great diflBdence the writer ventures to offer a few remarks on the problem before us. Were there any proofs that hot springs charged with carbonic acid existed, or had existed, in the Frankenstein traps, it would be easy to assign to such an agency the alteration of th(? magnesian sili- cate into a carbonate, the solvent power of acidulated water at a high temperature hieing well known ; but it does not appear that anything of the kind has been even suggested in the present instance, nor does the position of the deposits seem to tally with such a supposition. The weathered appearance which the serpentine exhibits, points, on the other hand, with sufficient clearness to atmospheric action; and the circumstances under which the magnesite is found, all accord with the theory that the principal meta- morphic agent has been rain-water. It seems difficult to understand how such a cause should be adequate to the effects produced ; but if we consider the analo- gous case of the decomposition of granite, we may perhaps gain some light on the subject. By the action of moisture derived from the atmosphere, and containing carbonic acid, the silicates of potash, soda, &c., in felspar rocks are (according to Mr. Jukes) converted first into carbonates and then into bi-carbonates, which are dissolved and washed away, leaving behind the nearly pure silicate of alumina, denominated kaolin, or china clay. Now it is known that if we add a small quantity of G 2 68 Observations on the Magnesite of Silesia. the solution of an alkaline silicate to a solution of hydrochloric acid, the silica, instead of being precipi- tated, is retained in solution, and may be separated by dialysis from the alkaline chloride and the excess of acid. There is thus no difficulty in supposing that silicic acid may be removed in a soluble form by acidulated water from rocks undergoing the process of decomposition, provided that the silicates are sufficiently amenable to the solvent fluid. To apply this to the case of the felspar of disintegrated granite, we may assume that the silicates of potash and soda are first dissolved by the carbonated rain-water, and that the silicic acid, set free by their conversion into carbonates, is then carried off with these in solution. The question remains, Can a similar theory be re- garded as admissible in the transmutation of serpen- tine into magnesite ? In both cases we have strong reason to attribute the effect produced to atmospheric action, and in both cases the deposit consists of a friable chalk-like substance, very free from iron or other colouring matters. But there is this important difference : the silicate of alumina derived from the felspar is the insoluble residue which remains un- affected by the chemical action that has taken place, while the carbonate of magnesia is a new substance produced by chemical action. In the first instance, the double silicate of alumina and an alkali has simply lost the silicate of the alkali. In the second case, the silicate of magnesia has been deprived of its silica and had carbonic acid substituted. Never- theless it is possible that there may be a closer Observations an the Magnesite of Silesia. 69 malogy than one would suspect between the pro- cesses that have taken place in the two cases. Bischof tells us that even those silicious rocks in which the silica exists in its less soluble modifica- tions are unable to resist the long-continued action of acids; and with so high an authority to support us, we may venture to maintain at all events the possibility that the magnesian silicate of the serpen- tine becomes gradually dissolved by rain-water charged with carbonic acid, in the same way as the more tractable alkaline silicates of the felspar, and that it is in like manner converted into a car- bonate. But the carbonate of magnesia is not like the carbonates of potash and soda, a readily soluble substance, and instead of being carried off in solution it would be precipitated as soon as formed, while the silica (supposing it to be kept up by an excess of acid) might, as in the former case, be washed away. We should thus have the magnesite deposited nearly pure, as we actually find it; and without pretending that there is any proof that this explanation is the true one, it may perhaps be deemed suflBciently con- sistent with facts to be accepted in default of a better. In Mr. Richter s pamphlet he directs attention to the fragments of serpentine frequently found among the debris of the old quarries coated on both sides with magnesite, and seems inclined to infer that one at least of the surfaces has undergone a metamorphic action since being detached by the hand of man from the adjacent rock. If this be so, it would in- dicate that the process of transformation is proceeding 70 Observationa on the Magnesite of Silesia. with great rapidity; but it may be safer to suppose that such coated fragments have been broken off from places where the serpentine rock has had a number of small fissures very near together filled with magnesite, in which case the line of fracture would naturally follow the course of the softer mineral, and might easily give rise to the appearance described. When nature acts by feeble atmospheric agencies upon such stubborn materials, we may well imagine that time has been (as in so many other geological changes) the principal factor in working out the result. November, 1869. THE GEOLOGY OF LUNDY ISLAND. By Nicholas Whitliby, Hotutraty Member ef the Soeietp, HE island of Lundy is three miles from north to 3uth, and rather more than half a mile in width, and kiroughout its entire length is composed of a mass of 3^anite, which forms bold cliffs on its western side, ind steep slopes with rocky cairns on the east. Its urface forms an undulating table-land about 400 feet ligh on the south, and falling in height as it narrows Q width towards the north ; the surface also inclines owards the west, so that the prevailing westerly winds ave a clear sweep over the island. At its south-eastern extremity there is a small atch of slate about half a mile in length, and ter- kinating at Bat Island, forming about one-tenth of le whole island. The map shows the position of the granite and 16 slate, the direction of the joints of the granite, nd the strike of the beds of slate, which are ccurately laid down by the compass. My object in laking the survey was to compare this outstanding atch of granite with the granite bosses of Cornwall, nth especial reference to the direction of the joints 72 The Geology of Lundy Island. and the contact of the granite with the adjoining slate. By referring to the map, it will be seen that the main joints have generally a north and south direc- tion, and that the lines are parallel to the line of junction of the granite with the slate, and form a curved line along the eastern side of the island, and thus indicate the probable extent of the granite boss, so that we are enabled approximately to trace its boundary by the direction of the joints, by the scattered islets, and the soundings on the Admiralty chart; and it becomes highly probable that the original boss formed an egg-shaped mass four miles long and three miles wide. The western portion, exposed to the full power of the Atlantic surf, has been much wasted away ; while the eastern side, being more sheltered, and composed of harder granite from its contiguity with the slate, has been but little denuded. The direction of the joints differs greatly from those of the granite of Penwith ; but they agree in this, that the joints in both cases appear to have a relation to the line of junction with the slate, and that the best developed joints lie on the line of the longest axis of the granite boss. The joints of the slate are parallel to those of the granite, and at the landing-place there is a well- defined elvan, about eight feet wide, running nearly in the same direction as the joints. The beds of slate strike E.S.E. and dip 80 deg. N.E., thus the beds abut against the granite, where The Oeology of Lundy Island. 73 bey are disturbed and sharply cut off. The slate is imilar to that of the Devonian beds of North Devon. The surface of the island, especially at its northern art, produces heath and coarse herbage. There is 10 well-defined soil or subsoil ; but the mould which upports the heath is formed of granite detritus, mixed vith peaty matter from decayed vegetation. It is probable that at the drift period the island was swept by ocean currents, and this is supported by the fact that the shores and sea-bed adjoining abound mih chalk flints and pebbles of foreign rocks. Fovemheff 1869, VOL. IX. H REMARKABLE SEA-WAVES, OBaERVED IK MOUNrS BAT, OOBNWALL, APBIL 24th, 1868. Bt John Jope Rogers. On the afternoon of Friday, the 24th of April, in this year, ^ I was driving from Helston to Penrose, and wa? surprised to see the spray of the sea dashing high above the horizontal line of the Loe Bar— a bank of shingle which alone separates the waters of the Loe from those of the Atlantic. This phenomenon is usually not observable except on the rare occasions of the heaviest south-westerly gales happening at high water of the spring tide. As the wind had been very moderate for twenty-four hours previously, from E.S.E. {i.e. off shore), and scarcely any wind was perceptible at the time, I left the carriage at the door, and, taking one of my boys as a companion, hastened to the Bar to ascertain the cause of so unusual a disturbance. We arrived at the sea-shore shortly before six p.m. |: New moon had occurred two days before ; i.e. on 22nd April, at eight p.m., and the time for high water on the 24th was shortly after six. This was the fourth tide after the new moon, and therefore one of the highest of that spring. A magnificent sight rewarded us. There was very little wind, even ^ Remarkable Sea-Waves. 75 Gtt the shore ; but the sea was a raging ocean of huge waves, such as are never seen except in the heaviest gales on that coast. We stood rivetted to the scene for nearly an hour. During the whole time, and long after high water, wave after wave beat home against parts of the cliff where I had never seen it reach before ; and for the first time in my life I saw the whole line of the Loe Bar (half a mile long) frequently covered from end to end by sea waves, which poured their foaming volume into the Loe. It was not one giant wave, followed by others of less formidable bulk (as has been usually the case on occasions of volcanic disturbances of the ocean), but a succession of hundreds of great waves for more than an hour continuously, and only varied in size as is usual with the seventh or eleventh wave in ordinary tides. The Bar had been cut during the previous winter for the purpose of setting free the swollen waters of the Loe, and the channel thus made through the shingle of the Bar had been kept open to the tide a longer time than usual, causing the scour of the tide to deepen and widen the channel to an unusual extent, leaving a deep indentation or creek on the inner shore of the Bar when it became again closed Up. This deep creek was speedily filled with shingle, thrown up by the big waves; and on the following inorning it was diflScult to believe that there had been a channel or creek at all, so completely was all appearance of it obliterated. Much damage was done to the coast for some H 2 76 Remarkable Sea-Waves. miles round the bay, the sea-waves eroding the soft earth at points rarely touched, and bringing down masses of superincumbent soil. Seeing the inroads thus made upon the coast, I began to fear for the safety of a sea-wall which had been completed at Porthleven a few months previously, but scarcely yet consoli- dated. We were anxious to return to Penrose by way of Porthleven, in order to see if my apprehen- sions were realized, but the hour and the increasing darkness warned us that we must hasten home by the shorter route. On enquiry next day, I found that my fears were justified. , The sea-wall was sixteen feet high and sixteen feet thick at the base, built of dry quarry stones, hard clay slate, set on edge, and well keyed-in together at the back, presenting a slightly concave plane to- wards the sea, with a vertical batter ; yet the waves, repeatedly following a curved hollow offered to them by a spur of rocks jutting seawards at right angles to one end of the wall, and thus concentrating their force upon one point of attack, scooped out from that part of the foundation a hole about ten feet wide by twelve feet high, breaking up and scattering in con- fusion the largest stones of which the wall was formed. I was assured by some of the oldest fishermen in Porthleven (and there are some very old ones) that they had never known such a sea with so little wind, and never but once knew the sea " come home " with such violence in a gale, i.e. in the winter of 1865-6. The agitation of the sea was so continuous and Remarhahle Sea-Waves. 77 protracted that I quite expected to hear of a heavy ^ale in the Atlantic to account for it; but I do not remember to have heard of its being traced to such a scarce. A considerable disturbance of the barometer was noticed by me on the day in question ; for it fell on the 24th half an inch (to 29 25), and rebounded a full inch during the next twenty-four hours: wind on 23rd, E.S.E., wind on 25th, W.N.W. ■ I shall be interested to know if the observations of more accurate persons support this brief notice. I should also like to know if any signs of subsidence of the coast have been noticed in Mount's Bay during the past half century, as I am persuaded that at Porthleven the recent encroachments which the sea has made cannot be attributed to any other cause. October 20^, 1868. NOTES ON THE QUARTZ REEFS, OR LODES OF SANDHURST, VICTORIA, AUSTRALIA, By W. Nicholas, Member of Royal Society of Victoria, In forwarding the foUowiDg notes relating to one of the most extenslYe and important quartz mining districts of Victoria, I think I should commence by explaining what has prompted me so to do. It has often occurred to me that there was a great similarity in many respects between our quartz reefs and the lodes I had seen in the St. Just mining district, Cornwall. But what more forcibly drew my attention to this subject was a letter which appeared some time since in the Cornish Telegraph from the late much-respected Captain Truran, of Ding Dong Mine, relative to some peculiarities of lodes which he had observed, such as the sides of lodes, or some portions of them, being polished and striated, &c. I may state that exactly similar circumstances to those he mentioned occur in our reefs or quartz lodes of this district. My object, therefore, is to give what little infor- mation I can with reference to the formation of these reefs and some of their peculiarities, believing it The Quartz ReefSy or Lodes of Sandhurst. 79 )ossible that you might look on your lodes, in con- lection with our quartz reefs, from a new point of new. Should I succeed in this, if there is any malogy, there is a remote chance that some light may be thrown on their origin. I will now proceed to give a few particulars con- cerning this gold-field from notes I made some years since whilst a resident there. The Bendigo gold-field is situate in what may be considered a large basin, formed by rounded hills composed of Lower Silurian clay-slates, through which run the gold-bearing quartz reefs. From the extensive denuding of these hills were derived those fabulously rich deposits of alluvial ahris^ and detritus discovered in the gullies. These gullies have been worked over and over again in a manner very similar to your streams for tin ever siDce the opening up of this gold-field in 1851. The palmy days of alluvial mining have, however, passed away, and the alluvial miner now makes his &i or £2 10s. per week only, by very hard work and long hours. The importance of this district has for many years depended increasingly on quartz mining. Bendigo Creek, which runs through the centre of the basin above-mentioned, takes its rise near the Big Hill, one of a range of hills which run irregu- larly to the north-west, and is a portion of one of the many spurs thrown off from the Great Dividing Kange which runs across Victoria from east to west. On this creek, and about six miles from its source, is situate the town of Sandhurst. The granite of which the Big Hill is composed is of a translucent 80 The Quartz Reefsj or Lodes of Sandhurst. bluish -white quartz, very little felspar, and mica in minute particles. It is an extremely durable rock to all appearance, and has been extensively used in the construction of the railway bridges, &c., in the vicinity of Sandhurst. In comparison with the granite of Lamoma quarries, I should consider it to be much finer grained. In tlie immediate neighbourhood of the granite, i.e. within three miles, the clay slates and sand- stones are of a firmer texture than further East. The gullies have yielded many large nuggets, some of them exceeding 100 ounces in weight; in fact, the gold is generally what the miners term " shotty," or " heavy gold,** and consequently is found near its original source, the finer gold having been carried farther down the valley. The quartz reefs really deserving of the name are very few, the quartz occurring as a rule in irregular spurs or veins varying from one foot down to one inch in thickness or less. Small veins, the width of which would be from about one to three inches, I have seen extremely rich, insomuch that they might be considered veins of gold rather than veins of quartz (of course, the quartz predominated); but these veins have no regularity either in their direction or continuance of gold or quartz. From between these three miles of hard crystalline strata and Sandhurst township occurs a softer forma- tion, in which are found some of the richest reefs of this colony, and perhaps of the world. The average bearing of the strata and reefs is 23** West of North. The outcrop of the slate and sandstone is often taken The Quartz Reefs ^ or Lodes of Sandhurst. 81 as a guide by persons travelling in the bush. Its use in this respect is not confined to the neighbourhood of Sandhurst, but is general in a large portion of the colony. These slates and sandstones are of the Lower Silurian age, the slates containing graptolites in great abundance. In September, 1863, I forwarded to the late Dr. Couch, for your Society, thirty- two specimens of minerals and fossils, which, I have reason to believe, were delivered. These will illustrate some of the fossils, &c., which are found on the Bendigo gold-field and in the neighbourhood of Melbourne. Among those from Sandhurst were Didymograpsus Murchisonii, D. Sextans, Diplograpsus Folium, &c.; specimens of slate and sandstones, and of the slate immediately adjoining the reef or lode; of slate and sandstone, showing the lines of deposit and lines of cleavage crossing each other ; specimens of quartz ; and anti- mony and quartz from the antimony reefs near Heathcote, about thirty-five miles South- East of Bendigo. These antimony reefs are worked for gold and antimony, the antimony being of secondary importance. The water-level in the quartz reefs varies in depth with the rise or fall of the surface, but in the gullies it was usually met with at about seventy feet in depth. I refer to it as in the past, in consequence of the numerous pumping- engines having destroyed the original level. The water is brackish, and not fit to be used in engines. Beneath what was the original water-level the slate 83 The Quartz ReefSj or Lodes of Sandhurst. and saDdstone quickly alter in colour, from the soft brown pink and muddy yellow to a dead heavy- looking grey and slaty-blue. At a depth of 200 feet, the major portion of the strata, or country, beyond a few feet from the reef, consists of an extremely hard metamorphic rock, with here and there a band of softer slate. Both slate and sandstone in the vicinity of the reefs contain isolated cubes of iron pyrites, and fre- quently faces of slate of great extent are covered by them. About 50 feet east of the Johnson s Reef, and at a depth of 140 feet, there is a stratum of these cubes (size -^ of an inch) held together, or cemented by slate, at least two feet in width. I should judge the proportion to be two-thirds iron pyrites. This is considered a good indication of the vicinity of quartz, and might be called " kindly country." Below the water-level these cubes of pyrites are in good preservation ; but above, near the surface in the lighter coloured strata, usually the only sign of their having been, is the empty cubical impression of them in the slate or sandstone, in which they have been imprisoned and have been decomposed by the ever- varying supply of moisture. Surrounding each of these empty cavities is found a red or reddish-brown stain. In the country, or strata, the pyrites occur as a rule in isolated cubes, but in the quartz reefs it is very often observed to be massive. Both slate and sandstone contain large quantities The Quartz Reefs^ or Lodes of Sandhurst. 83 of whitish mica. It is also frequeDtly found in the cavities and laminations of the quartz reefs, and is very deceptive, from its close resemhlance of gold by candle-light (underground). The mode of testing it, made use of by Uie miners, is through its refractive powers. From the peculiar flat form of mica it reflects light only in one direc- tion, whilst gold reflects the same shade on all its sides. In mining phraseology, when the substance under observation will not " stand the light," it is decided not to be gold, and any one can decide with certainty which is gold and which mica after a little practice and observation. Of course, under the light of the sun this doubt is less likely to occur, but the above remarks hold good in this case also. Mica throws oflTa silvery -grey; light gold generally a deep and rich yellow; but there is also what is termed "pale gold" of a much lighter colour; and again, a third form, " ruddy -coloured gold," which appears to be coated by copper. When cut with a knife, this ruddy colour is seen not to prevail through the gold, but only on its surface. The strata immediately adjoining the reef, on each side for about six inches in thickness, are quite altered in appearance. Above the water-level it is called the "ironstone casing," from its colour and weight. It is of a red ochre, or brick -colour, and its weight about three times that of the slate or sandstone against which it abuts. This casing is gold bearing. In former years, the early days of quartz mining, the casing of the reef was broken 84 The Quartz Reefs y or Lodes of Sandhurst. separately (from the quartz), and thrown away with the mullock, or rubbish, on the burrow. The term used by the miners for breaking the casing in this manner was " stripping the reef." This operation is always a tedious one; for it is usual to take only the outer portion, leaving about one inch standing against the quartz ; this, combined with the extreme hardness of the casing, which was found to blunt the picks and gads as fast as breaking the quartz, made me often think there was little economy in separating them, although the price of crushing at that time ranged from 258. to 85s. per ton, and the carting to the machine about 5s. more. I had another reason, and that Yfbs my having ob- served that between the casing and the reef (or the face of the quartz adjoining the casing) was often the richest portion of the reef, and consequently stripping the reef was a work which required either great care and judgment or a loss of much gold. As a proof of the large amount of gold that was thrown away in this manner, I may mention that all the old mullock heaps, or burrows, which were about the shafts, have been crushed, and that they very frequently yielded handsome returns. I think it probable that this altered slate, or casing, and the peroxide of iron which is found in such large quantities between the divisions of the quartz, have been formed by the same operation, viz., from the water percolating through the reef being laden with the decomposition of iron pyrites in the upper por- tions of the lode. I feel more confident in making The QtLartz ReefSy or Lodes of Sandhurst. 85 the above statement with reference to the formation of the peroxide of iron, from having observed in a level through which water from a reef had been flowing undisturbed for many months, that the portions of slate over which the water had passed wSre covered by a red deposit of about the eighth of an inch in thickness, and that this deposit had, I might almost say, precisely the same flowing lines as those so commonly found in the peroxide of iron formed in the natural divisions of quartz reef, the only appa- rent difference in the lines being that those deposited in the level were less waved. This, no doubt, would be caused by the greater strength and power of the constant stream fl&wing over them. Below the water-level the iron-stone casing dis- appears, or is changed into a soft black clay-slate, frequently containing brilliantly-polished faces, which, on being rubbed, stain the finger in a somewhat similar manner toplumbago. I have seen miners, who had been working in this casing, look almost as black as they would have if they had been working in coal. Quartz reefs, I may say, are entirely formed of quartz; the quantities of iron pyrites, galena, man- ganese, felspar, mica, and gold, &c., contained in them bearing but a very small proportion to it. And more especially the latter-mentioned article — gold, for I never heard of any miner grumbling at its excess, although it has been found in what I have heard Cornishmen call "great thuds." The gold that called forth this remark was found in the Energetic 86 The Quartz Reefs ^ or Lodes of Sandhurst. Claim, North Victoria Reef, just about the original water-level, and the greater portion of it was covered by a coating of peroxide of iron. The gold in this case occurred in the cavities of the natural division of the quctftz. The common term expressive of the shape of the upper portion of a reef is " saddle-formed." Reefs vary very much in their width, but the average of the principal and most permanent ones is about three feet. Quartz in the cap of a reef I have known to exceed 23 feet in thickness, and to be of sufficient richness to work the whole of it (in Latham and Watsons claim. Hustlers Reef). * On the Victoria Reef, in the old Albert Company's claim, I saw a cross-cut driven through a body of quartz, which I measured to be between 60 and 70 feet in thickness, from one wall or casing to the other. This large body of quartz was very coarse and poor, no portion of it being payable. I have no doubt that it was the cap of the eastern and western Victoria Reefs, two of the richest reefs in this district. " Quartz boils," as the miners term them, of nearly as vast a size, are, or were, to be seen on the New Chum Reef, the Windmill Hill, the Sheepshead, the Hustlers, and many others, but have been found to be too poor to work ; only occasionally have the two or three feet next the casing been found to be payable. The Victoria Reef attained an immense width in the Endeavour Company's Claim at 200 feet in depth, beinjg 40 feet in thiekness. The average yield of The Quartz Reefs ^ or Lodes of Sandhurst. 87 gold for this width was one ounce per ton, but this is an exceptional instance. The back of the reef (behind the casing) as a rule we find to be formed of sandstone and the footwall of slate. The back frequently presents the appear- ance of having been water- worn, just like the smooth faces of the rocks on a sea-shore. The quartz about the cap of a reef has no regular structure, but it is merely a great mass of hungry- looking quartz, containing but little gold or any mineral ; yet as we get deeper and farther away from the saddle of the reef, the quartz decreases in width and assumes a laminated formation. The laminse ruh parallel to the walls of the reef. On fracturing a piece of quartz with one of these faces, it would, as a rule, be foun I to be partly covered by slate, iron pyrites, galena, and gold. Galena appears to be a most kindly mineral for gold ; for most rare is the instance of any reef con- taining it, which is not found to contain gold, and that, too, in payable quantities. This remark will, I believe, apply to all the reefs of this colony. It is a generally received idea that all reefs con- taining iron pyrites contain gold, and I do not believe there is one reef in which iron pyrites are not to be ^found; consequently, all our reefs are auriferous, and no doubt they are; but unfortunately a few solitary specs of gold, or cubes of iron pyrites, will not make a payable reef. Experience goes to prove that the richer the reef is in minerals the richer it is in gold, and vice versd. 88 The Quartz Beefs^ or Lodes of Sandhurst. It is a common circumstance to find gold intimately associated with iron pyrites and galena for the very best of reasons; viz., that by far the largest quan- tities of these minerals are found to occur in the laminations. I have often seen gold and pyrites so mixed that I could not discern where the junction was. Auriferous pyrites sometimes so nearly assume the colour of gold that at a glance one is apt to say that it is pure gold, but on closer inspection the diflerence is easily observable; for it presents too brassy a look. At the same time, pyrites and gold seem to stare at you from the same spot, separately, and yet in one. In a specimen contained in the auriferous quartz collection of the Mining Depart- ment of Victoria there is a cube of decomposing pyrites of a dark colour, through which traverse tiny veins of gold distinctly visible to the naked eye. This specimen is No. 266, and is described in the catalogue presented to your Society. It was extracted from the Victoria Reef, Sandhurst, at a depth of 200 feet, the depth of the water-level being 150 feet. I have very often seen gold traversing galena in a similar manner to the instance above referred to. This is owing more, no doubt, to the greater differ- ence between the colours of galena and gold than in pyrites and gold, and not to its being more frequently the case. Perhaps the best proof I can give you, in lieu of the specimens themselves, in corroboration of the correctness of some of my statements, will be to refer you to the catalogue (which I have already cited) of The Quartz Reefs^ or Lodes of Sandhurst. 89 Eturiferous specimens in the collection exhibited by the Mining Department of Victoria at the late Inter- colonial Exhibition, held in Melbourne in 1866 and 1867. In this catalogue you will find specimens of quartz from all the important reefs and gold-fields of this colony described, together with a large amount of valuable information which has been collected by the mining surveyors and registrars' officers of the department, under the direction of Mr. R. Brough Smyth, Secretary for Mines, Melbourne. The general strike of the reefs is northerly. At nearly right angles to the strike, both the quartz laminations and casing are striated, caused apparently by a gradual motion and attrition of the strata. These lines do not show themselves in isolated spots only, but generally throughout the reefs. They are well marked, and run in an uniform direction, as above stated. In no case have I ob- served these lines more distinctly displayed than in the Williamson's Reef — a thin, small, but most regular teef. Where the quartz had been reduced to between two and three inches in thickness, it was composed of what might be called corrugated quartz. The laminations were only about the sixth. of an inch listant from each other. This peculiarity I found to :>btain for over 200 feet in length, and it gave the reef the appearance of having been deposited in a like manner to the adjacent strata. Of course, this quartz would naturally fracture mth its laminations; and when so broken, it pre- sented a dry, unkindly, pale appearance, possessing VOL. IX. I 90 The Quartz Reefs^ or Lodes of Sandhurst. no minerals or variations in colour. I need hardly say that we found no gold in the reef whilst it re- tained these characteristics. But in the short length of twelve feet it would burst out into a width of about three feet, composed of a pure white, fine, rubbly, and unlaminated quartz, containing the usual minerals, and yielding as much as twelve ounces of gold per ton. This reef was most regular in its bearing and underlie (eastern). West of the Williamson s Reef is the Sophia (western underlie), which proved to be rich, the first crushing from it yielding over ten ounces of gold to the ton, but I never saw a more wayward vein. The strike of this reef was northerly, and about two feet in six feet. This could be most distinctly seen, in consequence of the reef taking a sudden bend, and running off to the west in an undulating, graceful manner, not much admired, as you may readily con- ceive by the mining manager, when I tell you that with every wave it decreased both in size and rich- ness, as if bowing itself out of sight, which it eventually did in the roof of the drive put in to ^^ follow it. Whether it went away to surface again I never knew, nor am I aware that it was ever tested in its vagaries any farther than when last seen by the then manager, whom I may perhaps just as well inform you was myself. The back of this reef, as is usually the case, was composed of sandstone. Be- tween the sandstone and the casing we found a little |^ highly^polished slate. The sandstone was irregularly rounded £^nd very smooth, and looked as if it had at '^ - The Quartz Reefs ^ or Lodes of Sandhurst. 91 one time been exposed to the wearing influences of water. When the reef ran away flat, it carried the sandstone with the margin of slate still on its back. In the contorted portion of its course the quartz was thickest, and richest, in the hollows of the bends ; in fact, they seemed like small inverted gutters.* The lines of deposit in the slate of the footwall followed, or ran parallel with, the undulations of the quartz line for line with wonderful accuracy. I am enabled to state this from the circumstance of this being the first instance in which I saw clearly the planes of cleavage running at right angles to the lines of deposit. (These lines were most distinctly and beautifully defined, in consequence of the strata being composed of thin layers of a very dark blue and a white slate.) I, therefore, paid very minute attention to everything connected with the reef and the strata in its vicinity, making it as much as two or three visits daily, in order that I might see the slate adjacent to the quartz as it appeared freshly broken. This slate contained a fair sprinkling of very bright arid perfect cubes of iron pyrites of uniform size, being nearly the sixteenth of an inch square. I have found felspar in the Victoria reefs, and have in my collection the best specimen of it that I have as yet seen. In this specimen fine crystals of felspar occur on a crystalline face of quartz. I had a very beautiful specimen of small delicate crystals of fel- * The name given to the deepest and richest portion of auriferous alluvial 93 The Quartz Reefs ^ or Lodes of Sandhurst. spar held together by gold, which was found in the same reef. This was the onlj instance in which I ever saw gold in felspar. I have noticed in the Johnson's Reef that where tbe reef ran out in a wedge-like foim, its place be- tween the walls of the reef was supplied by a forma- tion of slate, very thickly studded with fine cubical pyrites, until the quartz again forms and takes up its rightful position. A similar formation to the above occurs in the Great Extended Coy s mine at Eaglehawk, which has proved to be very rich, yielding by the ordi- nary method of crushing alone as much as 5 ozs. 12 dwts. 12 grs. of gold per ton. On the Johnson's Reef the formation showed evidence of being lami- nated, as if it had been deposited in a similar manner to slate : the laminations were parallel to the strata on each side. The lava-streaks (local name) or dykes present us with some of the most singular features in connec- tion with quartz mining. They are composed of a soft amorphous clay, and have a dioritic appearance. They vary much in colour, from a dull, heavy, ab* sorbent brown to a bright yellow or green, the yellow often forming a band on each side of the brown centre. Both the yellow and green I have often found to be striated, and to hiave polished faces. They consequently have the appearance of being partially laminated, but are not so in reality. On all the main lines of reefs these lava-streaks have been met with, but are rarely welcomed ; for at The Quartz Reefs, or Lodes of Sandhurst. 93 their junction with the reef they materially affect it, either by cutting off the quartz abruptly or by de- stroying its regularity, and rendering it thin, poor, dry, hungry-looking, and much mixed with foreign matter. In an oval shaft, sunk on a lava-streak on the Victoria Reef, I observed that, through the lava being softer than the adjacent strata, it had crumbled away; that permitting its tortuous course, as it ran across the shaft, and back again, in about every 20 feet of depth, to be distinctly ^een. But the general direction it observed, i.e. its under- lie, if I may so call it, was very true. At the surface this lava-streak entered the shaft on the western side, making its exit out of the shaft on the eastern side' at about 170 feet in depth. At 200 feet in depth it intersected the reef, and completely destroyed what had up to that time been a well-defined rich reef of from two to three feet in thickness. On the Johns6n's Reef a lava-streak, underlying west, cut out one reef at the top, and, at a greater depth, another at the bottom. I thought it very probable that these so-called separate reefs were originally one and the same, which had been dis- placed at the time of the intrusion of the dyke, or lava-streak; but this is merely conjecture; for I had not, at the time of my visit, any leisure to examine this interesting fault. At a still greater depth, on the course of this lava-streak which w^as sunk on for communication between two levels, it was found that a number of quartz spurs, underlying east, intersected it, and formed a large reef on its 04 The Quartz Beefs^ or Lodes of Sandhurst. back, and thus accompanied the lava-streak on its course as deep as it was then prospected. This last feature rendered these lava-streaks more incompre- liensible to me than ever. They certainly appear to have a very close connection with quartz reefs, and, from my experience of them, may be followed as in- fallible guides to the reefs, which at the same time would afford very easy sinking. The contour of the hills of this district can, I believe, be accounted for by the form of the quartz reefs. Viewed from the north or south, they are rounded and almost always gently sloping. From the east or west they may, in a measure, be con- "sidered to be serrated, or saw-formed. Each hill has a length or breadth, the bearing of the length being similar to that of the reefs, about SO"* west of north the slopes from the summit to the north being very gradual ; whilst to the south, in comparisori, they are abrupt and precipitous. You will observe in the longitudinal sketch-section of reefs forwarded here- with that they have a general strike to the north. On the tops of the north slope of the hills the quarts reefs are generally found to crop out on the surface, and, as a natural consequence, being harder than the country in which they are situate, offer greater resist- ance to the denuding elements. On those ranges in which the quartz does not crop out, as a rule there will be found the ironstone casing or " burnt sand- stone " of the miners, which is extremely hard, and offers just as much resistance to denudation as the quartz itself. The Quarts Reefs^ or Lodes of Sandhurst. 95 From the top of the hills to the south the " crown" or "cap of the reef" is broken through, and the strata, or country beneath it, is exposed without any protecting cap, and so is the more readily acted on, and presents a bolder declivity. In the early days of this gold-field, before quartz mining was commenced, fine tors, or immense bodies of quartz, occupied the summit of nearly all the hills, and must naturally have added very much to the picturesque appearance of the then wooded country. And as the face of the country got cleared of the timber, they must have stood more boldly out, break- ing that smooth, even rounded, appearance which the hills now have. I am informed, from reliable sources, that in those early days when quartz mining was not dreamt of by the majority, it was the usual pastime of the diggers on Sundays to take hammers, go up to these beautiful outcrops, in most of which gold could be seen, and break out specimens. The only remarkable one of these which I recollect stood out on the north side of New Chum Gully. The sole reason of its not having vanished like the others before the advance of the Anglo-Saxon race must have been its exceeding poverty. I have often watched it, when passing near, with a jealous eye, fearing that some speculative miner would, notwith- standing its poverty, be sufficiently enterprising to peg off the ground on which it stood, and eventually destroy the last of the race of quartz outcrops left on this field. But it was destined to be placed on " the roads" — a rather ignominous term in this colony; 96 The Quartz Reefs y or Lodes of Sandhurst. and I must own I was sorry indeed to find that such was to be the case. On the morning of the 26th August, 1862, to my surprise, I found some men had commenced boring operations, prior to blasting the quartz ; they proved to be road-contractors, who were about to make my old friend, into road metal, and, as I could not prevent them doing so, I decided on doing the next best thing, viz., making a sketch of it as it then stood. At the present* time there is scarcely a vestige of it left. Its dimensions, as roughly measured by myself, were — ^height, 20 feet; length, 36 feet; width, 4 feet 6 inches; underlie east, about 1 foot 6 inches in 6 feet. These oat- crops were slight evidences of the immense denuda- tion the face of this district has suffered in past ages. 1 In bringing this paper to a conclusion, I would beg to draw your attention again briefly to the facts before stated, that all our reefs in this district are of a lami- nated structure, i.e. a little below the cap of the reef; that in these laminae most of the gold and minerals are found, in addition to slate, mica, and sometimes felspar, and that it is my belief that such is the case throughout the reefs of Victoria. (In making this remark it will be as well that I should state, that although my experience of quartz mining has been gained in the Sandhurst district, I have examined and described good average quartz specimens from every other mining district in this colony.) The reefs of the Sandhurst district run parallel to the adjacent strata, and the upper portion of every The Quartz ReefSy or Lodes of Sandhurst. 97 reef terminates in a cap, or, I believe, did so prior to its being denuded of it, so their formation has the appearance of an inverted V. At more or less dis- tance, directly beneath the upper reef, another occurs, so far as I have observed, totally distinct and . separate from one another, and this supposition holds good to the greatest depths as yet proved in this district. The quartz of nearly every reef is striated in its laminse, or on its sides. The slate and sandstone adjoining the reefs (and sometimes the reef itself) have, more or less, polished sides. These phenomena appear to be evidences of a consistent and regular movement in the strata in which our quartz reefs are- situate. I may state that I am a mere gatherer of such facts as are presented to you, holding no special theory or theories of my own on the formation of quartz reefs. VOL. IX. K MEMOBANDUM ON THE DISOOYERY OF HAZEL-NUTS IN TIN STREAM AT ST. HIURY. By Thomas Cornish. Eablt in December last some hazel-nuts, in excellent preservation, were found, about 18 feet below the surface, in Tregilso stream-works, in Saint Hilary. The formation of the ground in the stream- works is described by workmen employed in it as Surface Mould, Clay, " Rab," " Shingle," " Run," or Water-worn Stone, " Turfy," qy. Peat, Stream Tin Stuff. The nuts were found in the " turfy" formation. This stream-work lies in the valley between Ha3fle Estuary and Mardzion Marsh. The workman who found the nuts, and gave the above information, states that some few years ago he worked in a stream-work near Wheal Darlington, in the same valley as the first, and about a mile west of it (the pit with the remains of an engine on it south of the railway, about half a mile east of Marazion Station) the formation there was — The Discovery of Hazel-nuts at St. Hilary. 09 Marsh surface, *' Turfy," qy. " Peat" soil, Sand, mixed with small white shells in great numbers, but mostly much injured, " Turfy," qy." Peat" soil, Tin stream. In the lower " turfy" or " peat" soil were found nuts and quantities of some hard wood. October, 1870. NOTE ON CHROME IRON IN THE SERPENTINE OF THE LIZARD. By Bichard Pearce, f.g.s. In the summer of 1862 I observed in several lumps of serpentine which I examined small granular particles of a black, hard mineral, which proved to le chrome iron. I am not aware that the occurrence of this mineral in the Lizard serpentine has been noticed before by mineralogists, although I can hardly imagine that it has escaped the observation of those who have minutely studied the mineralogical characters of the rocks in that district. The books on mineralogy which I possess make no reference to Cornwall as a locality for chromite, and I have thought that it might not be out of place i 100 Chrome Iron in the Serpentine of the Lizard. for me to ask the Geological Society to notice it in their Transactions. The specimen which accompanies this paper I found in a quarry near Cadgwith. I have thought it of sufficient interest to estimate the quantity of chrome iron contained in the stone; it amounts to 1'80 per cent. An analysis of the sample, contained in small tube, yielded 30 per cent, of sesqui-oxide of chromium, which represents -3 9* 3- per cent, chromic acid. In addition to the ordinary constituents of chrome iron, I detected a trace of copper equal to about 010 per cent. Minute particles of iron pyrites were also visible by the aid of a lens. October, 1870. !(OTE ON A GRANITE BLOCK AT HALAMANNIN6. By Richard James. 30UT twelve years since, whilst inspecting the alamanning mines, in the parish of St. Hilary, in mpany with one of the resident agents, I had my tention drawn to what I considered a most curious lenomenon. At about sixty fathoms from surface, sinking a winze from one level to another, they id suddenly met with a large block of granite, very uch in the shape of a bullock, but much larger, id imbedded in the killas, in which strata this mine as entirely worked ; in fact, there is no granite jcurring in its neighbourhood nearer than the odolphin Hill, in Breage, on the east at about le distance of a mile and a half, and St. MichaeFs [ount on the west also about one mile and a half istant. I have been asked whether this block was ot perhaps a cropping-up of the granite formation om below the killas, which has occurred in some of le mines in the Camborne and Redruth districts, at 16 junction of what they term the North and South rranites. But this I conclude was not the case, as 16 granite bed must be hundreds of fathoms below le point at which this curious block occurred. In le course of conversation a short time since with a 103 A ChraniU Block at Hakmanning. genUeman who is deeply interested in all that con- cerns the geological formation of this county, he deemed it advisable that I should communicate the occurrence to this society, thinking that perhaps some of its members might be able to throw some light on this matter as to the formation. October, 1870. MEMORANDUM ON PITCHBLENDE IN COLORADO. By Bichabd Pearce, f.g.b. I HAy£ sent for the Geological Society a specimen of pitchblende (oxide of uranium), which I discovered a few weeks ago in Bussel District, Gilpin County, Colorado Territory. It is the first time, I believe, that the mineral has been found in America. It occurs associated with auriferous copper and iron pyrites at the junction of gneiss and mica schist. I found about 2 cwt, which had been thrown away on the refuse-heap, and the person in charge of ibe property told me that it caused them a great deal of inconvenience, as it had come into the lode and cut the copper out. You may imagine his surprise when I told him it was worth in England about <£400 per ton I MoBFA Works, Swansea, October 27ih, 1871. NOTE ON PITCHBLENDE IN CORNWALL By Richard Pbarce, f.g.s. HE recent discovery of pitchblende at Wheal Owles, t. Just, is interesting, as affording a new locality for lis mineral; and I have no doubt the Society has Iready been favoured with particulars of its occur- 3Dce in that district. I am induced to offer a few remarks relative to the )Qditions under which this mineral has been found 1 Cornwall. Pitchblende almost invariably occurs associated; ith other rare Cornish minerals, and the laws which ppear to regulate its deposit in various localities are rikingly analogous. At St. Austell Consols it was found with nickel and )balt ores, and a quantity of this valuable mineral as sold as an ore of uranium. At Dolcoath, where I found it in 1859, it was ssociated with native bismuth and arsenical cobalt 1 a matrix of red compact quartz and purple fluor par. At South Tresavean I discovered it in 1863 with upfer- nickel, native silver, and rich argentiferous alena. 104 Pitchblende in Cornwall. I believe in all the localities I have named it was found in little veins crossing the lodes. The St. Just pitchblende, however, so far as I have been able to ascertain, does not occur under similar conditions to those I have before named. I have found, however, traces of lead and silver in the Wheal Owles mineral. In the specimen which Mr. Boyns was kind enough to send me, I find the physical characters differ some- what from pitchblende found in other localities in the county. The colour is reddish-brown ; structure, somewhat lamellar; specific gravity, 4'95. The peculiar grouping of certain minerals, and their relation to the rocks in which they occur, is a • subject meriting more attention than it has hitherto received from English mineralogists, and no better field than Cornwall can be found for study in this particular direction. % ON TEACES OF GLACIAL ACTION ON THE GREAT CAIEN, NEAR GORRAN HAVEN, cornwall. By C. W. Peach, a.l.s. At the meeting of your society in October, 1848, a paper of mine was read On the Geology of Part of the Parish of Gorran^ Cornwall^ and was afterwards printed in vol. vi. of your Transactions. At page 56 mention is made of the " slickensides " on the large blocks of quartz rock at the Great Cairn, and that " some pieces from the highest point were as highly polished as if done by a lapidary." Those pieces I have great pleasure in sending with this for your inspection and acceptance for your museum. They are all I have, and were got out with diflSculty, owing to the extreme hardness of the rock. They were broken from the horizontal face of the upper mass which crowns the pile that shows so conspicuously in the cliff above Peraver. Although a sniall sample, it is highly characteristic, not only of the rock itself, but shows well the polishing by glacial action, and to those conversant with such polishing cannot be mis- taken for slickensides. When I lived in Cornwall I knew nothing practically of the appearance of glacial action; had I, it is probable I might have done better. 106 Traces of Glacial Action. Even at that time I was so much interested in seeing tlie quartz blocks scattered far and wide, that at pp. 56 and 57 of my paper they are particularly noticed, and the places where ihey lay, although I was unable to say how they had been dispersed. It would be well if some one would examine them, and the deposits of stone and clay-matter in the cliff on the side of the stream that flows through Gorran Haven, and as well the deposit of blue clay at the back of the fort near the place. In all probability polished and striated stones would be got in these localities, showing glacial markings. When in your county, in 1869, I visited St Keverne, to try to find the Porthalla limestone. Un- fortunately, the wet weather was against me. Despite of this, I devoted as much time as I could spare to examine the pile of quartz rocks under the Nare Point. Slickensides was there, like that of Gorran Haven, and also scattered blocks, but no polished surface. All around for miles the wide-spread ruin of former rock deposits might be seen, blocks of all sizes lying thickly. To me they prove that ice only could have removed them and laid them where they are. Atmospheric influences have acted on them, and lichens have grown on them; and thus all the markings of transportation and grinding are lost Lichens would also cover markings on most of the quartz blocks. The only way to get at fresh mark- ings would be by turning up some of the imbedded rocks and examining the underside, as well as the upperside of rocks when bared of their protecting Traces of Glacial Action. 107 covering of earth and grass, whether for quarrying or other purposes. By this method I have been fortunate enough to find traces where those on the exposed surfaces had been lost. With the poHshed specimen from the Great Cairn I send one of quartz rock for comparison, taken from a huge mass near EriboU House, on the side of Loch Eriboll, Sutherlandshire, in 1857, You will see that the polishing is much alike in both, and I feel no hesitation in stating that both were done by glacial action. That from Sutherland shows it best; it evidently was exposed and acted on by long- con- tinued heavy glaciers ; for all the surroundings show how powerful and extensive they must havfe been, both by the wide-spread ruin and extensive scratch- ing and polishing seen for miles. On the other side of Loch Eriboll rises Ben Spionnu, 2,566 feet above the level of the sea. The quartz rock slopes iroxn the top to the bottom of this mountain into Loch Eriboll, passing under the limestone island in it, and rises again in the hill on the House of Eriboll side of the Loch, and is there again covered by limestone from the Loch side to the spot where it shows -itself nearly vertical on the hillside. The quartz rock on the side of Ben Spionnu has been grooved and polished in the most surprising manner at more than 1,000 feet up its side. I have followed it for hundreds of feet, from ruts deep enough to hold your fingers, up to the highest polish, some of it brighter than that sent from near Eriboll House. This polishing is not vertical, but horizontal. Seen 108 Traces of Glacial Action. from a distant hill when the sun shines on it, t rays glitter as if striking upon acres of polish glass. Although non-glacial, I cannot resist saying tb the quartz rock of Sutherland is full of arenicolik identical with those I found in the quartz at Gre Peraver, and which at page 67 of my paper I calk " a coral very much like the recent sabellaria alveokta The likeness to these sandy tubes i& complete. Hov ever, I know now that they are not coral, and thf they were made by the annelide above mentionec It is thus interesting to know that these two siluria quartz rocks contain similar organisms; viz., arem colites ; it further adds to the interest that they ar also found in the silurian quartz rock of the Stipe stones, Shropshire. Specimens of the Cornish aren colites are in your collection. I must apologise fc troubling you with this trifle ; my excuse is, so littl has been written on Cornish glaciers. I am, howeve glad that Mr. Whitley Taas so ably taken up th subject, and I hope he will go on. I should b delighted to be a fellow- worker with him. The reason the specimen now sent was not i your possession long since is, it turned up only short time ago, after more than twenty years' repo< amongst other Cornish things packed before I le for Scotland. I trust it will prove worthy of accep ance. Haddington Place, Edinburgh, 2Qth October, 1871. i THE GEOLOGY OF PENZANCE BAY AND ITS SHORES. By Nicholas Whitley, Honorary Member of the Society, The long and rugged coast-line of Cornwall presents favourable opportunities for the study of its geological structure, and nowhere are more interesting sections exposed by the abrasion of the sea than around the Bay of Penzance. From a survey of its shores at low-water, and an inspection of the seaward rocks by boat, I have con- structed the accompanying map, showing the position of the rocks, their strike, dip, and the direction of the joints. The structure of the country inland is taken from the Ordnance Survey. I purpose only to make some general remarks on the geological features of the Bay, without entering on details, and to draw such inferences as the facts appear to suggest. It will be seen from the map, that at the N.E. of the Bay the beds of slate and greenstone run S.W. The smaller patches of greenstone are clearly seen to be bedded in the slate, on the same line of strike; and the larger bosses of greenstone partake of the same general direction. Westward to Penzance, and 110 The Geology of Penzance Bay. southward to Mousehole, these beds curve with the shore of the Bay, and run parallel with the edge of the granite behind them. In some places the green- stone passes into hornblende slate, and the whole mass appears to be contemporaneous with the slate in which it is bedded; in other places the junction of the two rocks is well defined, and the slate is twisted both in strike and dip by the greenstone. These massive hornblende rocks which skirt the Bay — which have governed its outUne, and have given fertility to the soil on its slopes — form part of that extensive and ancient outburst of volcanic matter, the ashes of which now form, beds of trappean conglo- merate among the Devonian slate, and its more com- pact parts, the greenstone bosses, which circle around the afterwards erupted granite, or cap the headlands of our coast. But the geological history of the Bay centres rather in modern than in ancient periods ; and there are records written on its shores which cast some light on the changes through which it has passed. But, dwelling for a moment on its ancient form, the solid ground of Devonian slate and hornblende rock must have extended further than at present into the Bay, and perhaps far beyond it. The now naked elvan courses and the exposed trap-rocks must have been coated with thick beds of slate when they were erupted. The Gear was once a portion of the main- land, and the Long Rock and the Oressars were clothed with beds of slate long, long before their more fragile covering was devoured by the sea. The The Geology of Penzance Bay. Ill trap-rocks, from Cudden Point to the Greeb, are four patches of the tail-ends of beds which once extended far across the entrance of the Bay. But the modern deposit of drift inside the Eastern Green indicates a period of greater interest. The drift is exposed in the railway cutting near Wheal Darlington Mine, and in many open pits around it forms a tongue of land extending into the valley, and may be traced to New Town and beyond. It is com- posed of water-worn pebbles of quartz, elvan, granite, greenstone, altered slate, and, some water-worn chalk flints, and covered with a soil, the ruin of the adjacent land above, at the base of which is some angular detritus, crushed quartz being the most abundant, and shattered flints and flakes. In an uncultivated croft adjoining the new turnpike-road, denuded of the upper covering of the soil, the crushed flints and flakes may be found on the surface mixed with broken quartz. These beds of drift correspond in every respect with the so-called " raised beaches '* which are found in patches clinging to the ancient shore-line of the Bay, a section of which has been lately exposed in excavating for building at and near the Penzance gas-works, where water-worn pebbles and fine sili- ceous sand form a stratum at the base from 2 to 3 feet thick, covered with 20 feet of clay and loam, mixed with angular rocks of greenstone from the hill above, from a few inches to 8 or 10 feet across. These beds are stamped with all the geological elements which constitute the drift period. 112 The Geology of Penzance Bay. Water- worn pebbles of local rocks are mixed with foreign materials, and covered with a confused mass of clay and angular rocks, pitched in at all angles, some so large that only ice action could have torn them from their native bed and lodged them in the confused mass of clay and stone in which they are now found. The drift at Wheal Darlington obviously came down the valley towards Hayle, and over its low- water parting ; and I have traced backwards the trail of similar beds from the Scilly Isles, along the north coasts of Cornwall and Devon to South Wales. They are also found on the west coast of Wales, on the Isle of Man, and over the county of Down, up to their native site in Antrim. The pieces of basalt, " white limestone," and baked flints, stamp a cha- racter on these drift beds which make their identity unmistakable. On the east coast of Ireland this Antrim drift may also be traced as far South as Cork. How far these beds extended seaward cannot now be determined. That they filled the whole of Pen- zance Bay appears certain from the patches which remain along the shore, and it is probable that they extended far beyond, if not quite across the English Channel. And here I would notice the instructive fact, that, on examining the greenstone rocks of the Great Hogus, which extend far out into the Bay, I found the remains of the loamy subsoil, with angular stones, at about the half-tide level, and similar to that on the mainland. On these beds of drift, which once choked up the i The Geology of Penzance Bay. 113 Bay, grew the ancient forest, the remains of which are now found below the sea-level at Lariggan and near Marazion, and described in the Transactions of the Society. The last movement of the land appears to have been downward, and, as it sank, the sea excavated the Bay, leaving patches of drift clinging to its shores, and throwing up the shingle and sand at the Greens, which now protect for a time the portions of the drift-beds behind them. November 3r(i, 1871. VOL. IX. ON THE BONES OF A WHALE FOUND AT PENTUilf. NOW IN THE MUSEUM OF THE BOTAL GEOLOGICAL 80CIET7 OF OOEinrALL. By William Henbt Flower, f.r.&, Hunterian Troft—or of Oamparative Anatamp, and Cknuervator of the Muteum 0/ tk0 JKoya/ CMiege of Surgeon* tf England, The fourth volume of the Transactions of the Royal Geological Society of Cornwall contains a paper (read October, 1829) by the late Mr. J. W. Colenso, entitled, " A Description of Happy- Union Tin Stream-work at Pentuan." Reference is there made to certain organic remains found at various depths in the works, and which were presented by the author of the paper to the Society, and are now contained in the Museum at Penzance. Among these are several bones rightly identified at the time as having belonged to " a large whale," an account of which it is my object to give in the present communication, as I believe they have never been described, and the species to which they belong has not hitherto been determined. For the particular circumstances under which the bones were discovered, which are of very considerable geological interest, I must refer to Mr. Colensos paper. I may, however, mention that tlie works The Bones of a Whale found at Penman. 1 1 5 were some half-mile or more from the present sea- shore, and about sixty feet in depth, the greater part of which is below the sea level, and that the whale bones were found at a depth of rather more tlian twenty feet from the surface in a stratum of sea sand, above which was a bed of rough river sand mixed with gravel, and below were several distinct layers of sea sand and silt, containing timber trees, chiefly oaks; remains of various animals, as red deer, oxen, and boar; human skulls (one of which is now in the Museum), a piece of oak fashioned by human agency; and lower down, stumps of trees in sitUy moss, leaves, hazel-nuts, &c. ; still further down being the tin ground, lying on hard rock composed of blue killas, and on account of which the works were undertaken. These conditions clearly indicate that at one period the spot was dry land, and the site of a forest; that it subsequently became submerged to a considerable depth below the sea, at which time the whale would have been stranded; and that it has since been restored to dry land, either by a re -elevation or by the accumulation of sand driven up by the sea, together with gravel washed down from the neigh- bouring hills. As to the date of the whale's stranding, I will not venture to oflFer a conjecture; but the evidence appears conclusive as to its having been subsequent to the occupation of the country by man and recent animals, as the red deer, but so long back as to have allowed of the accumulation of upwards of twenty feet of sand and gravel above it. L 2 116 The Bones of a WhaU found at Pentuan. The bones mentioned by Mr. Colenso, all of which are now in the Museum, are: 1, the right ramus of the mandible, or lower jaw; 2, a lumbar vertebra; 3, a humerus; 4, a radius; 5 and 6, two metacarpals, or phalanges. There is, every reason to suppose that they belong to the same individual, and are in much the same condition, being nearly white, as if bleached by exposure on the beach, entirely free from oil, which so strongly pervades all recent whale s bones, heavy and dense in texture, though not in any way mineralized. They are thus quite diflFerent in appear- once from the human and animal remains which were found below them, and which all have the characteristic deep brown colour, resulting from contact with decomposing vegetable matters. The animal had probably attained its full size, though it was not old, as the epiphyses were united at both ends of the humerus, though traces of their original separation remained, and both of the disk- like terminal epiphyses of the body of the vertebra were absent. It is perfectly evident that they belong to no species of whale known to exist in the British seas; indeed, the peculiar form of the jaw and the pro- portions of the other bones are different to those of any species of whale described, with one exception, and that is one of which a skeleton was found, under circumstances in some respects similar to the present one, in the Swedish island of Graso, in the Baltic. In that case, fortunately, the skeleton was far more complete than in the present instance, and as all the The Bones of a Whale found at Pentuan. 117 bones have been excellently described and figured by Professor Lilljeborg, of Upsala,* there is no diflSculty in making a satisfactory comparison. This specimen was found in draining a field, where the bones lay partly in sand and partly in clay, at a depth of two to four feet, ten or fifteen feet above the present sea- level, and eight hundred and forty feet from the shore, and in conjunction with the shells of Mytilus edidis and Tellina baltica of precisely the same ap- pearance as those now met with in the Baltic, indi- cating a period when the general physical features of the sea were as now, but anterior to the elevation of the island to its present level. The length of the entire skeleton was estimated at between forty- five and fifty feet. It was originally described by Professor Lilljeborg under the name of Balcenoptera rohusta, but it afterwards constituted the type of Dr. Gray's genus Eschrichtiu$,\ which designation has been adopted by Lilljeborg in his more recent and detailed memoir above referred to. The following comparison of the dimensions and characters of the bones of the two specimens will show the grounds upon which I infer their specific identity. It will be observed that the Cornish specimen is throughour slightly inferior in size to that from the Baltic : * On two sub-fossil Whales discovered in Sweden, Nova Acta of the Royal Society of Sciences at Upsala, ser. 3. vol. vi. 1867. Also Ofversigt af Skandinaviens Hvaldjur (Upsala Univeraitets Arsskrift, 1861-2) ; trans- lated into English in Recent Memoirs on the Cetaeea, published by the Bay Society, 1866. t Annals ani Magazine of Natural Historyy vol. xiv. p. 343. 118 The Bones of a Whale found at Pentuan. AAMUt OF MAKBIBLB. Pjotuan <^rta3 ft. in. ft. m.* Length in straight line . . , . 7 6 8 2 Height at condyle . . . . 1 2^ 1 5 Hei<>ht at coronoid process . . . 10 11 Height at middle 10 10| The bone is remarkable for its massiveness and great vertical depth, which is pretty nearly equal (about ten inches) for the larger part of its extent. The condyle is large, and separated by a deep horizontal groo?e, on the inner side only, from the prominent angle. The coronoid process is represented only by a low nodule, the anterior edge of which is twenty-four inches distant from the hinder end of the bone. Near the upper edge of the outer surface are seen seven large foramina for the exit of nerves. The whole ramus is very little curved, a condition speci- ally remarked on by Lilljeborg in the Graso specimen. The vertebra belongs to the lumbar region, though its exact position in the series cannot be determined. Its dimensions, as compared with the third and the sixth of the Graso whale, which are given by Lillje- borg, are as follows : Q^^a Pentuan fhiid sixth in. in. in. Length of body 7^8^81 Height of body in front . . . 7} 7} SJ Width do 9 9 9i Distance between tips of transverse pro- cesses .36 35^ 37 Height to the top of the spinous process . 22 21 * I have given LiUjeborg's figures in Swedish feet and inches, which aie slightly smaller than ours, so that the bones of the two specimens axe moie nearly one size than appears at first sight. The Swedish inch 19 0*9742 English inch. The Bones of a Whale found at Pentmn. 119 It will be seen that it corresponds best with the ( sixth in general dimensions, allowing for the some- what superior size of the Graso individual, but differs in the comparative shortness of the body, which is, in fact, the most notable point of difference between the two specimens. The bones of the limb, which are preserved, agree very well in form with the figures given by Lilljeborg. Their dimensions are as follows : HVMBRV8. Pentuan OrigS Iiength 20i 2U Breadth at middle 9 9^ RADIUS. Length (imperfect) 26^ 29^ Breadth at upper end ..... 6 6^ Ditto at middle 6^ 6} Ditto at lower end 8| 9 * These bones have been much damaged, the radius especially having both extremities broken and worn. Of the two bones of the hand, one is certainly a metacarpal, as it has an oblique articular surface at one angle of the proximal extremity, in addition to the principal terminal articulation. It is 6*8 in. long, and 4*4 in. wide at the proximal, and 5*1 in. at the distal end, and corresponds in form and size very closely to one figured by Lilljeborg. (No. 72, pi. vii.) The other bone, which appears to be a proximal phalanx, is 6*8 in. in length, 3*4 in. in breadth at the middle, and 4*9 in. at either extremity. It is ^^— ^^— ^— ^ ■■»■ I » ■■■■!■ ■ l» I — I ■■ ■■■l»^^— ^^^— ^1 I I 11 ■ ■■ — ■ * Some of these dimensions are taken from Lilljeborg*s figure, as they are not given in the text. ISO The Bones of a Whale found at Pentuan. slightly larger than either of the four phalanges of the Graso whale which have been discovered, but these probably belong to a more distal part of the manus. With so close a correspondence in dimensions, as well as general characters in such different parts of the skeleton (the discrepancies which exist being quite within the range of individual variation), we are obliged to assume the specific identity of the two specimens, although, of course, admitting the possibility that such an assumption might prove in- correct if a large number of bones were found. The two other recorded evidences of the existence of the species are less conclusive, inasmuch as each is based upon a single bone. The first is a cervical vertebra in a mutilated condition, wanting the nearal arch, cast ashore in Babbicombe Bay, Devonshire, in 1861, and described and figured by Dr. Gray.* The second is a ramus of the lower jaw, preserved in the Museum at Rutgers College, New Brunswick, N.J., which Mr. Cope says " is of peculiar form, and closely resembles the figure given by Lilljeborg of that portion of this rare species." f With regard to the systematic position of Eschrich- tins robmtus there can be no doubt but that it belongs to the family Balcenidce, or Whalebone-whales, though it cannot be placed in either of the three principal genera into which the group is divided; viz., Balcemi * Proceeding 8 of the Zoological Society , 1865, p. 40. Catalogue of t^^ Seals and Whales in the British Museumy 1866, p. 133. t Froc, Acad, Nat, Science, Philadelphia, 1868, p. 184. The Bones of a Whale found at Pentuan. J 21 Megaptera, and Balcenoptera. It agrees with the two latter in having the vertebrce of the cervical region distinct from one another, and with the former in the rudimentary condition of the coronoid process of the lower jaw. Its relations have however been suflSciently discussed by Lilljeborg. The interesting question remains whether this species still exists in our seas; if extinct, it must have become so at a comparatively recent period, certainly long after Cornwall was inhabited by man. The negative evidence of no specimen having been met with by naturalists in a living or recent state is hardly conclusive as to its non-existence, as our knowledge of this group of animals is lamentably deficient. We are acquainted with many species even of very large size only through isolated individuals, and the discovery of others new to science is by no means an infrequent or unlooked-for occurrence at the present time. October 26ih, 1872. SOME REMARKS ON THE MINING DISTRICT OF YORKE'S PENINSULA, SOUTH AUSTRALIA. Bt Samuel Hiogs, Jun., F.a.B., f.g.s.c., J7oMor«ry Mtmh^r of tk4 Imperial 80eUtp of ArU and Beieneea cf L^on9, #e.; UUe Seeretarp to tht Roffol Oeologieal SoeUtjf cf Oomwali; SupormUmdmt of the Waliaroo tmd Dooru Mima, #e. I CANNOT but feel some degree of diffidence in pre- senling my observations on this important district to the Society, which will be the more readily conceived when I mention that I can find no record of this district ever having had the advantage of being visited by those great geological authorities, whose vaguest hints even often give a clue by which the lesser lights are enabled at times to approach, with some degree of confidence, such a subject as I shall now attempt. Yorkes Peninsula is that tongue of land lying west of Port Adelaide, bounded on the east by Spencer s Gulf, and on the west by St. Vincent's Gulf. It is about 150 miles long, and varies in width from 25 to 50 miles. It is a country entirely destitute of fresh water, except in three or four places on the sea-shore, where wells have been sunk in the sand and some brackish water found, which, for want of better, cattle drink. The country from The Mining District of Yorkes Peninsula. 123 the Hummocks range of hills, situated at the head of the peninsula, to the extreme south point, is nearly a dead level, undulating slightly in one or two places. The only natural vegetation is a stunted mallee tree- scrub, the foliage of which is a dirty olive green. At certain seasons of the year its sombreness is relieved by the yellow blossom of the wattle-tree, with now and then a clump of native peach-trees, and an occasional bush of the native myrtle, with its diminutive white flower. The grass, known as spear- grass, after rains, grows rapidly, and for a month or two, in some places, affords fair feed for sheep ; but a day or two of a South Australian sirocco (north wind) dries it entirely up, and the whole face of the country assumes the aspect of an arid wilderness. Of animal life there is but little. Kangaroos, in some parts, herd in considerable numbers; and the wallaby, a small kind of kangaroo, is to be met with occasionally. That extraordinary burrowing animal, the wombat, may sometimes be seen of a fine moon- light night. There are several varieties of snakes and lizards, amongst them the iguana. Of birds, in the quiet parts, emus are sometimes met with ; there are two or three varieties of hawks, of which the eagle hawk is the largest; the wattle bird — the shep- herd s companion — a small variety of woodpecker ; and several varieties of the parrot tribe, with magpies and ravens. These constitute just the whole of the wild denizens of the district. The native population is small, numbering, it is thought, 160 all told; their numbers never exceeded, 124 The Mining District of Yorhes Peninsula. perhaps, 350. The smallness of the tribe may be accouDted for by the scarcity of water : the same reason may also account for the smallness of the native population in so many parts of Australia. I am not inclined to speak so disparagingly of the aborigines as the writers of some books are : I see pretty much of them, and find them to be shrewd observers, with a great fund of humour, and inimit- able caricaturists. The climate is a most trying one, and perhaps in no part of the world are the ranges of temperature so great. Often, during the daytime even, has my ther- mometer noted a diflference of 40 degrees. The hot winds and dust-storms hurled along from the dry parched plains of the north are at times almost unbearable ; to work is altogether out of the question. During their continuance, all nature seems gasping, and birds soon succumb to their baneful influence. • The average rainfall is 10 J inches; the rainy months are June, July, and August. Such is a general outline of the country, its in- habitants, and climate. And now I will pass on to its geological features. Undoubtedly the surface rock or crust, and some of the overlying rocks, are of a very recent formation. To generalize, at first, I would state that as a rule the rock of the district is clay-slate, overlaid by a bed of unconformable limestone; in one or two places there is an overlying rock on the clay-slate, of a very recent tertiary formation, intensely hard, which makes k The Mining District of Yorkes Peninsula. 125 excellent building-stone ; but even this recent forma- tion has the same overlying bed of limestone. On the east coast, on the shores of Spencer s Gulf, from Parrara to Black Point, one might almost say that a bed of this tertiary rock is to be seen gradually forming ; for, the fossils, in the rock itself, are identical with the shells, Crustacea, and other living organisa- tions to be seen and found on the sea shore. Midway between these two points, in a sandstone formation, is a large deposit of phosphate of iron; at Black Point, the clay-slate protrudes, and here are to be seen several promising copper lodes, which, no doubt, wlien the metal commands a higher price, may be profitably worked. I am informed that the same recent formations of rock are to be found all the way down this coast, the clay-slate being occasionally exposed. Crossing the peninsula, about midway between the two Gulfs at Boors' Plains, is the bed of hard tertiary rock previously mentioned : it appears to be an older formation than the one just described. It is quarried for building purposes, but not to such an extent as to enable one to decide how it lies in connection with the clay-slate on either side of it. The bed would seem to run north and south, as I believe it is a continuation of the same formation to be seen some three miles further north, of which I shall presently have to speak. Reaching now across to the other coast, St. Vincent's Gulf, so far as I have been able to trace it, clay-slate appears to be the exposed rock, except about five miles north of the Port of Wallaroo. Here are several large courses or 136 The Mining District of Yorkes Peninsula. dykes of quartz, running into the country in an east and west direction ; and immediately north of these another kind of rock, gneiss, comes in. How far this rock extends I cannot yet ascertain; and besides, even to trace it now on paper, would take me beyond the boundaries of York's Peninsula. The bed of unconformable limestone thus overlying the whole of the lands of the Peninsula varies in thickness from a mere crust to three and a half feet. In places it is intensely hard to break through, and in others it is very friable; as a rule, immediately under it is a bed of clay from three to twelve feet in thickness, but occasionally the rock is struck im- mediately under the limestone. Having thus given a general outline of tHe geology of the district, I will now proceed to give some par- ticulars of its mineral deposits. Indications of copper on the Peninsula were observed, in 1869, by a gentle- man who then held the district as one of his outlyiog sheep-runs. Having picked up on the beach, near the site of the present smelting-works, some green- ore (muriate of copper), he became convinced that deposits of this mineral existed inland. It is not for me to dwell on the months of toil and hardship that gentleman went through before he had the satisfac- tion of proving that his surmises were correct ; suffice it for me to remark that one happy day, in the year 1860, when exploring one of the dense mallee tree- scrubs, he came across the workings of a wombat; and there, thrown out and scattered over the debris of the hard limestone crust, so patiently dug through The Mining District of Yorkes Peninsula. 127 by that extraordinary animal, was quite a burrow of green-ore. Pits were quickly put down, and very soon the back of the great Wallaroo lode was laid open, and its course traced up. This discovery was quickly followed by others of equal importance. Such then is the origin of the discovery of copper in this district, which so soon had to play an important part in the world s market for this particular metal. Without further preface, I will now proceed to give some description of the nature of the deposits, and will take, in the first place, THE WALLAROO DISTRICT. The main bearing of all the productive lodes is from 20 to 24 degrees south of east and north of west; and up to this time I have not seen, nor am I aware of, any copper in quantity being fouud in any lode much out of this bearing. The lodes warp in places considerably, and just at the angle of their so doing they are the most productive ; if they continue in a straight line with smooth walls they soon become poor. The great Wallaroo lode, for the greater part, dips south, at an angle of 15 degrees; but in one place, where it has been very productive, it is almost vertical. The underlie here, if any, is slightly to the north. It is worthy of note, that where the lode is vertical, the quality of the ore is much richer (2J per cent, produce, at least) than where it takes an underlie, Milnes lode and North Mairs lode dip north, at an angle of about 12 degrees; the same remark, as to 138 The Mining District of Yorkes Peninsula the increased richness of the ore when the lodes take a downright course, applies also to these veins. The Wallaroo main lode has been worked on for rather more than two miles in length, but not in all cases productiTely. I mentioned, in generalizing the geology of the district, that its rock was clay-slate. Now, to par- ticularize the mineral-bearing rock. It is now laid down as an established fact, that unless the clay- slate carries with it a considerable quantity of mica, or, indeed, unless it assumes almost the character of a mica schist, the lodes will not carry copper in pay- able quantities: hence one of the reasons of the occasional non-productiveness of the Wallaroo lodes, and the cause of so many disappointments. Another cause of disturbance in the lodes is the numerous slides and faults. The slides are most irregular, but all the principal ones have a tendency to throw the mineral deposits westward ; this is plainly shown now in our deepest workings — 120 fathoms— -where the main shoot of ore is carried away bodily by a slide. Here, again, is another matter, I think, worthy of note. At the point where the lodes are cut off by the slides, they are more productive ; and the same thing is observable when they are picked up again on the other side of the slides. The lodes are not rich in either metallic or earthy minerals ; — copper, hsematitic iron, tourmaline, schorl, in their respective forms, and manganese— (in this latter ore, from the back of more, than one lode, I have found traces of gold and silver) — quartz not well The Mining District of Yorhes Peninsula. 129 rystallized, two or three varieties of calcite, and ccasionally molybdenite near the change of the Dpper ore from muriate to the sulphide, constitute 1st the whole; barytes near the clay is sometimes let with. In one or two places a small cross-vein as led to small deposits of galena, not rich in silver. About three miles north of Boors* Plains, close ) where there is evidently a continuation of the 3rtiary formation I have alluded to, considerable uantities of lead have been raised, and the whole f the surface is covered over with nodules of hse- latitic iron. The mine has been abandoned for ome years, so that I am not in a position to give urther particulars about it. I am not prepared, in this paper, to say anything bout the cross -courses or their influences on the odes ; in fact, they have not been suflSciently proved warrant my hazarding any remarks about them. All the lodes in this district have been found by urface indications, either from green -ore being arown out by the wombats, or worked up by some f the burrowing insects. This green-ore is almost invariably a muriate; ometimes the copper is found in the form of a grey ulphide adhering to the limestone crust, oftentimes oated over with a layer of lime. In the former ase, the lode can easily be traced up and the ore asily taken away, for the ground is generally soft; be green-ore lasts down as a rule about 13 fathoms, ^hen it changes to a black oxide, and very soon after -say another three fathoms — to the usual sulphide VOL. IX. M 130 The Mining District of Tarkes Peninstda. of copper, more or less mixed ap with iron pyrites. If the lode is very prodactive, the iron pyrites gives way entirely to its more valaable associate. There is one thing to note respecting tliis iron pyrites ; it is generally on the productive lodes found in the hanging wall, so that, when dressing the ore, the iron pyrites is easily picked out. Where the surface ore takes the form of a grey sulphide, it soon changes to a red oxide, not unfre- quently intermixed with malleable copper, and which soon changes to the sulphide of copper, perhaps at an average depth of 12 fathoms. The surface deposit from a lode of this sort is much richer than when the back forms a muriate. In the one case the percentage of ore may average 20 per cent. ; in the other, 10 per cent, would be considered good; but this diflFerence of quality as regards surface-ore does not hold good with the sulphides under: the quality under both would be about the same. The size of the lodes varies considerably, from 20 feet to one foot wide. ^ The great shoot of ore on the Wallaroo Mines at the 40 fathom level was 16 feet wide of solid ore, of 12 per cent, produce. The water in all the mines is intensely salt. Fortunately for pitwork, there is no free acid with it, hence little inconvenience is felt in this respect; but as it is the only water we have to condense with, the boilers corrode very quickly, and have to be cleaned every six or eight weeks. The quantity of water in the district cannot be The Mining District of Yorkers Peninsula. 181 considered excessive, and it would appear as if there were two main water-courses — one about 17 fathoms in depth, and the other from 45 to 70 fathoms. Below this, there is only water enough for the usual requirements of the mine. It is estimated that over 250,000 tons of 12 per cent, ore have been returned from this district since the first sales in 1861 to the present time. Thb Wallaroo Mines, 2nd January, 1872. M 2 ENQUIRY INTO THE NATURE OF THE FOECES THAT HAVE ACTED ON THE FORMATION AND ELEVATION OF THE LAND'S END GRANITE. Bt the late Miss Elizabeth T. Cabne. This district possesses special advantages for such an enquiry. The other granite masses of Devon and Cornwall have been elevated in the midst of other formations, and their central situation and covered flanks give little opportunity of gathering together the facts necessary to support any enquiry into the nature of the forces that have acted on them. Our Western granite, on the contrary, is largely surrounded by the sea, and possesses a variety in its internal and external structure, which may perhaps supply us with facts on which to base some fair and reasonable de- ductions. I. Let us notice the internal structure of Cornwall. If we look at a geological map of Cornwall, we shall see that the various granite bosses (including Dart- moor) lie on lines which approximate to E.N.E. and W.S.W. So, too, the large majority of the mineral veins and elvan courses run a little N. of E. and S. of W. ; the greenstone bands also ; though 1 question if these do not need further investigation. With Elevation of the Land's End Granite. 138 occasional exceptions, all this holds good throughout Cornwall. II. There is the external configuration of the whole surface ; and on this head we have to distinguish between original structure and structure which has been superinduced. The very first question is, Are our valleys valleys of erosion or otherwise? If of erosion, the whole superficial structure has been superinduced, and in no degree bespeaks any pecu- liarity of structure in the original formation. But if not of erosion, any parallelism in the system of our valleys points to some law which has probably in- fluenced the original structure. It is the fashion to consider all valleys as valleys of erosion, unless they can be proved to be otherwise ; but certainly he must be much blinded by a theory who can see valleys of erosion in West Cornwall granite. In the first place, the narrowness of the land from sea to sea supplies Qo water suflScient to cut such valleys. If it be said that the land might have been ten times as broad in past ages, that does not touch the point in question, for we have manifestly the central portion remaining, \he backbone of the watershed. If the land had stretched from Mount's Bay to France, it would not liter the fact that it is only five miles from Mount's Bay to the granite ridge between St. Ives and St. Fust, which is the head of our streams of water. Five- nile streams could not cut such wide valleys in any apse of ages. Small streams would cut a little channel suflScient for their own small course, and ;hey would sweep away all loose stones and gravel 184 The Formation and Elevation long before they would cut through tough granite, leaving us bare rocky water-channels instead of our wide and rounded hills and valleys. There is no doubt that erosion has acted on our valleys, it acts on everything ; but, inasmuch as it is utterly insufficient to cut out our valleys, they must be referred to some antecedent cause. Mr. Whitley, long ago, pointed out that the Cornish valleys form parallel lines running from N.W. to S.E., and having often sharp bends at right angles to this course; also that N.W. and S.E. is the line of the predominant joints of the rocks; and he suggested that a common law ran through both series of phenomena. This, then, is the first thing that strikes us as probably betokening original structure, a series of predominant joints and valleys running from N.W. to S.E., with cross joints and cross valleys at right angles to the first. III. There is the structure of the granite itself, and of this there are three forms well marked in their extreme types, though continually passing into each other. 1. That in which perpendicular joints predominate, and which forms clifis much resembling basalt in aspect, as may be seen in many places between the Land's End and Tol-Pedn- Pen with. 2. That in which horizontal joints predominate, and which forms Tors, pre-eminently characteristic of Dartmoor, but which may also be seen at Carn- brea, and on the range of granite hills between Zennor and St. Ives. 3. That which belongs to our best and hardest of the Land's End Granite. 186 granite, where both sets of joints are less prevalent, and which therefore forms deep courses in our quar- ries, and huge masses on our earns and cliffs. Con- sidering that some kind of force has produced the most prevalent joints, we may regard this third form of granite as simply due to the absence of such forces, and therefore limit our enquiry to the two other forms of granite, that distinguished by tabular slabs, and that resembling basaltic pillars. Here analogy may help us. Anyone who has been in a basaltic country like Madeira, or who has seen or read an accurate account of modern lava, is well aware that both basalt and lava may be seen in precisely these two extreme forms. Where surface movement or surface influences have predominated, the lava and basalt take a hori- zontally laminated form, the air-vessels are elongated in the direction of the motion, the texture is vesicu- lar and scoriaceous through rapid cooling, and the harder portions lie in narrow slabs horizontally with the mass. But in lower beds, or in lower parts of the same bed, the basalt, and less frequently the lava, takes the upright pillar-like form with which we are all familiar in pictures of Staffa and the Giant's Causeway, and which is expressed by, I believe, an invariable formula, " Main joints at right angles to the surface." My inference is, not that granite, and basalt, and lava had the same origin (which would be a rash conclusion), but that they have come under the in- fluence of the same forces. I regard the predomi- nance of tabular forms (the result of predominant 130 The Formation and Elevation horizontal joints) as essentially a surface structure — the structure which bears a presumption on its face, tliat, of the whole mass to which it belongs, it has been most exposed to external influences. Those in- fluences may comprehend lateral movement, or rapid cooling, or lessened pressure, or altered chemical conditions. We must go elsewhere for proofs of any or all of these; but I think we may fairly venture to say that the structure itself does bespeak more of the influence of external agencies, vhile, on the other hand, the predominance of pillar -like forms (the result of predominant perpendicular joints) bespeaks more of agencies inherent in the nature of the rock itself. All quarrymen will bear witness that it is rare to find granite at the top of a quarry that will come out in fine square blocks. We can see for ourselves on entering a quarry, by the cracks on the sides, how apt the granite is to lie in shallow layers near the top. Whatever has been the cause, it does seem to be a surface structure ; and I use the term " surface' in the widest sense, meaning that part of the mass which has been most exposed to external disturbing influence. I must remark that this appears to me a rule of some practical importance to quarrymen. I noticed at Zennor how often the hills were scarred by attempts at quarrying, but the granite was gene- rally of a coarse description. According to my views, the chances were ten to one that it would be so, when right over my head on the hillside lay the great tabular earns, which showed that the whole of the Land's End Granite. 137 hill was surface granite. On the other hand, do not many of us remember the beautiful upright masses of granite on the east side of Lamorna Cave, which Mr. Freeman has blown to pieces? They were the result of perpendicular joints; that is, of more un- disturbed crystallizing forces in the granite; and the chances were that the rock around them would be hard and fine-grained. Some years ago I was at Chagford surrounded by tabular tors, but the granite is poor and the softest I ever saw; but at Hey Tor they have good granite quarries, and I saw there what I never saw elsewhere— the abrupt junction of the two sorts. There is, or at least there was, a great mass there like a gigantic mushroom : the overhanging part was in great quadrangular blocks, and of very coarse texture; the under part was in perpendicular blocks, and of beautiful fine-grained granite, with the line between them as sharp as that between the pillars and the laminated beds of a mass of basalt. But I must admit that this rule will not bear universal application ; for the granite at Sheffield quarry, in Paul, is said to be the best in the neighbourhood, though tabular slabs are to be found on the hill westward of it and at Castallack Cam. And I think it possible this rule may not apply at all in other localities, and for this reason : that when the granite has risen in inland districts under a heavy mass of slate, the great pressure to which it is subjected may produce hard, fine-grained granite even in close proximity to the tabular earns, which bespeak disturbing external agencies. I think 138 The Formation and Elevation we must look to pressure as the probable agent which interferes with the different forces that produce both horizontal and perpendicular joints. Where the granite has been so compressed that it can yield neither to external influences nor to internal crystal- lization, there we shall probably find it the hardest and most free from joints. The good, quality of the Sheffield and Lamorna granite supplies a suggestion that that district has been subjected to unusual pressure. IV. There is the composition of the granite. The mixture of quartz, felspar, and mica, to which we give that name, is subject to great variety, of which hand specimens may be procured in every part of the district; but looking on our rocks in the great mass, I think we can only distinguish three principal kinds of granite. 1st. Our common quarry stone, in which large crystals of felspar occur in a mass of mixed felspar, quartz, and mica, and which prevails over the whole district, if we except St, Michaels Mount. 2nd. Ludgvan granite, which is found in small masses in several parts of that parish — a rock remarkable for its whiteness and abundant glistening mica. Of this sort are the granite pebbles, found on the eastern end of Marazion sands, and also, I think, the chief mass of St. Michaels Mount; but I say this doubtfully, not being able to chip even the stained sea rocks of that close preserve of granite. 3rd. Our so-called "moorstone" — a very small- grained mixture of mica, quartz, and felspar, which is found lying loose on the moors around Oastle-an- of the Land's End Granite. 139 dinas, Choon Castle, Bosphrennis Hi]l, &c., and also (and this deserves notice) on the tops of some of our highest hills, Trecrobyn and Pertinney, as also on Carnbrea, in the Redruth district. This stone diflfers from our common granite, not only in composition, but in structure, being found in flat, angular, shapely pieces, needing little squaring with the hammer to fit it for building purposes. It forms our dryest, toughest, best building stone. V. There is the dip of the rocks. The old theory was, that the elevation of the granite had simply thrown off the slate on every side of it; and in corroboration of this, we were told that the dip of the beds between Newlyn and Mousehole was S.E., as we might expect it to be, and at the Gurnard s Head N.W., as we might expect it to be. Now, even as much as this needs qualification. If it were a little S. of E. at Mousehole, it should be due E. at Newlyn and the western rocks of Mount s Bay ; but it is not, it is fully as much S.E. at the Wherry Rocks and round the Battery Rocks, and at Chyandour Rocks, as at Mousehole. Also, on this theory, the patch of slate at Rosemodris should dip due S., and that, too, dips S.E. Also, all the rocks around Lelant should dip E., and they, too, dip S.E. I gmnt indeed that the Gurnard's Head should dip to the N.W., but unluckily its beds dip to the N.E., and so on the great scale do most of the cliffs around Zennor—at least, a little E. of N. — when any dip can be plainly discerned. As far as my observation goes, I do not hesitate to say, that all around our 140 The Formation and Elevation coast there is a predominant dip towards the E., that from Carbus- water to the Logan Rock the dip is S. of E., whilst all around the Zennor coast it is N. of E., or rather, perhaps, K. of N. I do not think this can be explained by the mere elevation of the granite. Then there is another objection to the elevatory theory of dip. This dip towards the E. southward on one side, northward on the other, is shared by the granite itself — shared to the full. S.E. is the prevalent dip of our southern granite: N E. is the dip of the granite at Wicca Pool. This shows beyond all ques- tion that the force which has produced the prevalent dip of our rocks has acted equally upon both rocks, and is not the exclusive result of the elevation of the granite. Here, then, are the materials with which we have to deal : 1st. The internal structure of the country, common to the rest of Cornwall. 2nd. The external configuration of the country, common to the rest of Cornwall. 3rd. The structure of our granite. 4th. The composition of our granite. 5th. The dip of both granite and slate. The next step is to go rapidly through these various points in their application to the Land s End district. 1st, as to internal structure. If we compare the form of our granite with other granite bosses, we shall perceive that it is of a very peculiar form. It first forms a long line from St. Ives to St. Just, and i of the Land's End Granite. l4l is then bent southward and eastward to the Logan Eock and Paul, and finally bent again in a projecting piece westward to the Land s End ; in short, it is something like a reverse form of the letter Z. If we look at the el vans, they run approximately on E.N.E. and W.S.W. lines all through the country till they reach Sancreet. It is diflBcult to trace elvans through granite, but we are told that that which occurs at Bosava runs N. and S., also that at Mayon, near the Land's End. If we look at the bands of green- stone (though, I repeat, I think these so much need further investigation as to be worth little in the argument), we find them running through the country approximately on E.N.E. and W.S.W. lines until we come to Paul Hill, where the great green- stone band is bent round N. and S. If we look at the mineral. veins, we find them chiefly (with one or two local exceptions) running through the county approximately on E.N.E. and W.S.W. lines till tliey come to Morvah; then a blank space ensues, and immediately follow the whole of the St. Just veins, running chiefly on N.W. and S.E. lines. In the mass of granite bent to the south no veins of any consequence have been discovered, while at the same time the valleys of Lamorna and Sancreet contain the largest deposits of stream-tin in the neighbour- hood. The one exception seems to be the Garth Mine above Buryas Bridge, where the veins run E. and W., resembling the rest of the county, and not the neighbouring parish of St. Just. We must notice also that the valley of Nancherrow forms a line of 142 The Formation and Elevation disturbance in the dip of the tin veins, those to the N. of it dipping S., while those to the S. dip N. 2nd. If we look at the external configuration of the district, we shall see a series of hills and valleys and prevalent joints running on N.W. and S.E. lines, in this agreeing with the rest of the county. We may note especially the valleys of Nancledrea, New Mill, and Madron or Ding Dong, and in the southern part of the district, Lamorna and Penberth. But in Sancreet we find a district of disturbance, and the valley line which runs from Eelynaok to Drift and Newlyn is almost W. and E. 3rd. If we look at the structure of the granite, we see a great line of hills more or less marked by tabular — or, as I deem it, surface — structure, running from St. Ives to Pendeen, and then bent to the south at Carn Bosavern, south of St. Just. After that it almost disappears; po.ssibly it may be found on Pertinney and the Sancreet hills, but I have not been able to hunt for it; and it exists in a feeble form at Castallack Carn, and on a hill west of SheflSeld Quarry, and on Paul Hill, and in a quarry at Rose-an-beagle. But its almost total disappear- ance is a marked characteristic of the southern granite, just as the presence of basalt-like granite is characteristic of our western cliffs between Tol Pedn Peuwith and the Land s End. Our object now is to enquire what forces and what circumstances will so far harmonize with and explain this variety of facts as to supply us with some reason- able and probable conjectures as to the formation of the Land's End Oranite. 143 and elevation of the West Cornwall granite. I have no intention to enlarge upon the various theories of the origin of granite, but I must just touch on the three principal ones. The first is the theory of eruption; that granite as a molten fiery mass was pushed from below into contact with slate deposited by water from above, as lava might be pushed into contact with later stratified beds. The insuperable objection to this is the uniformity of the circum- stances that attend the junction of granite and slate — the intimate commingling of their elements, even while the line of division is sharp and clear — felspar saturating the killas, and the dark substance of the killas creeping into the granite; but still more than this, the invariable presence of a band of purple killas round every mass of Cornish granite forbids us to attribute their junction to the hap - hazard influences of eruption. It is a law, not a chance, which has connected the two. 2nd. There is the theory of metamorphosis, some- times so broadly stated as to present no other idea than that all slate is decomposed granite, and all granite recomposed slate, a theory equivalent to* the assertion, that of two successive forms neither was formed first. More moderately expressed, this theory asserts, that though granite is metamorphosed and reconstructed slate, slate must be assumed to be the disintegrated product of some rock analogous to granite that has ceased to exist. But why should we call up needless difficulties in the shape of pre- existent non-existent rocks? If we can conceive of 144 The Formation and Elevation rocks formed prior to their disintegration, we have that conception to begin with, and must not beg the question of their being metamorphosed, short of proofs of metamorphosis. I dare not say, having only local knowledge to support me, that granite is not recon- structed killas ; but I have never been able to detect the slightest proof of it, whilst even in West Corn- wall there is abundant proof of the identity of killas and greenstone. Even in the face of written testi- mony, I venture to assert that the metamorphism of granite rests rather on the credit of great names than on the strength of sound inductions. Lastly, there is the contemporaneous theory, which has met with deserved objection by being put forward in a literal rather than in a large sense. Considering how little we can know of the formation of rocks which takes place deep under the earth or the sea, it would be folly to say that the formation of granite and slate was actually simultaneous. And I think no one can see an extensive junction of granite and slate, as in that splendid instance for a quarter of a mile round Wicca Pool, without admitting that the slate was ' certainly in a less plastic state than the granite, for the fragments of slate are sharp and angular amidst the surrounding coils of granite. Either it had been formed a little earlier, or it had set and hardened sooner. All that should be understood in the term '' contemporaneous " should be the close relation of the circumstances that have influenced the formation of both rocks, and of the forces that have acted on them. The close attendance of the of the Land^s End Granite, 146 killas on the granite, the commingling of their sepa-^ rate elements, and the parallelism of the veins, elvans^ &c. that run through both, seem to attest the subjec- tion of one to the forces that acted on the other. Hence, amidst the slow operations of nature, we think of them as belonging to the same era in formation, though one mighf have been the first page and another the second. Now let us recall the internal structure of the whole of Cornwall, and part of Devonshire. Masses of granite in various parts on N.E. and S.W. lines, with bands of greenstone (though I think these need investigation), elvans, and mineral veins on the same lines. Is there any theory to account for this? Mr. Hopkins has attributed them all to universal magnetic forces acting on N. and S. lines. But it is rather a wide interpretation to find the proof of meridional, that is N. and S. forces in lines that lie N.E. and S.W., nay, rather nearer E. and W. Still we know that the magnetic pole was once east of the true north, and we might suppose that Corn- wall assumed its internal structure in that far-distant period. All the more, if, as has been said, these N.E. and S W. lines are of common occurrence all over the world. It is such a pretty theory. I have turned it round and round, trying to fit it into the facts ; but, unhappily, Mr. Hopkins s whole theory supposes that the forces come from the S. to go to the N., while the facts say that they come from the N.E. and pass to th6 S.W. I have no theory to offer. If the forces that influence structure rose rapidly from the centre VOL. IX. N 146 The Formation and Elevation to the circumference of the earth, they would acquire a bend from E. to W. by the increased rapidity of surface rotation, as currents in the atmosphere do in the phenomena of the trade-winds. But we have no knowledge of the precise action of the earth's internal forces. I prefer, therefore, without any attempt at theory, to take the existence of N.E. and S.W. forces for granted, and to regard them as structural forces, that is to 'say, not accidental disturbances, such as volcanic eruptions would be, but as forces that have the nature of a law (though at present we are ignorant of its precise nature), such as magnetism, heat, and chemical affinity. I regard these forces as having acted on what is now Cornwall while it lay deep beneath earth or sea, while the granite or slate were forming, or before they had lost their first plastic elasticity. Among these forces I seem to recognise one re- sembling that which is still apparent in earthquakes, a great undulatory movement, to which I think we must attribute the subsequent elevation of the granite and slate, and also certain effects which took place even before it rose or while it was rising. What else but a great undulatory movement could produce a whole system of hills and valleys and predominant joints — and may we not also include cross-courses?— all at right angles to its course, that is on N.W. and S.E. lines ? What else could produce such wonder- fully uniform effects — one greatwave following another, producing pressure on the same lines of resistance, and tension, and fracture on the same lines of weak- of the Land's End Granite. 147 ness, as resistance was overcome ? Undulation acting on the granite while it was settling would produce swelling hills and valleys ; undulation acting on the granite while it was shrinking would produce predomi- nant N.W. and S.E. cracks or joints. I used to think these might be due to some incipient law of crystal- lization, but I do not see how this could act alike on such different substances as greenstone, granite, and slate, and they all share in the predominant N.W. and S.E. joints.. I do not see any other interpretation that can possibly meet all the facts. A central point of elevation would not do it, for we should have had a system of radiating valleys and joints, and of radiating dip in the rocks all round a centre ; and a line of elevation would not do it, when the valleys were manifestly too wide to have been produced by erosion. On all these grounds, I venture to assume that the force which elevated the granite was an un- dulatory force. And now I must recall what was said of the sur- face structure of granite; namely, its tendency to form tabular slabs from the prevalence of horizontal joints. While it was rising, or even before it was rising, if lessened pressure allowed it any kind of expansion, an undulatory movement would tend to roll or stretch it, probably causing it to assume this structure, until the whole surface hardened and set in a series of flat shallow slabs, or onion-like curves, the fragments of which we still see on the tops of quarries and in tabular earns. How come they to be such fragments? Let us think. An undulatory 148 The Formation and Elevation force coming from the N.E. would tend to make perpendicular joints at right angles to it, but it would act against the horizontal joints, or tabular slabs, straining and shattering them in every direc- tion. More than this, the lines of shrinkage would be on N.W. and S.E. lines, and as the granite in drying gaped and parted, down would go the hori- zontal slabs, smashing themselves in pieces. That is exactly what we see — lines of earns on our sea cliffs, with intervals of soil and angular stones be- tween them, and loose stones all over our moors, deeply imbedded in granite gravel. The loose stones are (as it were) the knots in the wood, the hardest bits of the tabular slabs; the gravel is the decom- posed representative of the soft, shattered surface beds. And now let us see how this undulatory force would act on the west of Cornwall. Most of the other masses of Cornish granite have a circular form. It is the form of equilibrium, speaking of balanced forces around it; but the West Cornwall granite is twisted out of all shape. Plainly the forces around it were not equally balanced. This is what I conjecture to have happened from its har- mony with existing facts. The undulatory move- ment coming from the N.E. struck the N.E. corner between St. Ives and Hayle (and this I think must have happened very early, before the internal struc- ture of the whole of Cornwall was fully developed; for which I will give my reason hereafter) ; tut the granite was perhaps. a little hardened at the sides of the Land's End Granite. 149 nearest the slate, and the slate, perhaps, with its crystalline greenstone bands, was a little harder still, and the granite was pinned down, partly on the N., but still more on the S., and instead of rising in a circular mass, it stretched out in a long line from St. Ives to St. Just; then it was jammed again by another bit of slate and greenstone, and was bent round to the S., wJiere, perhaps, it met the remainder of the granite struggling upwards under the Mount's Bay beds of slate. Now, what would happen if this took place? I have- assumed that though the granite between St. Ives and St. Just was confined in its course, it was not greatly disturbed, not more disturbed than the granite in the inland parts of Cornwall. It would, therefore, retain something of its external tabular structure, and wholly its internal structure of N.E. and S.W. mineral veins ; but, as it drew near St. Just, it would be fearfully disturbed. The granite would be turned round in St. Just parish as on an elbow, producing enormous strain and fracture on N.W. and S.E. lines, and the surface beds would be shattered jn pieces, being exposed to a double strain — first by the undulations against the horizontal joints, then by the wrench round to the S.E., at right angles to their previous direction. And now what do we see in St. Just? A disturbance in the N.W. and S.E. lie of the valleys, a cessation of the N.E. and S.W. mineral veins, and a whole network on new lines in St. Just, on those very N.W. and S.E. lines which would have been produced by the tension and frac- 160 Tlu Formation and Elevation ture of the granite, had the mass of it been bent to the south. Also we see the entire disappearance of the surface tabular granite south of Pertinney. The pressure on that twisted portion has been enormous, and the wreck has been immense; therefore it is that in that southern district we have our best granite, the result of greater pressure, and our best and deepest granite soil, the result of greater wreck. But how about the disappearance of tin lodes and the existence of tin streams in that southern district? Is it so certain that there are no tin lodes? If, indeed, none are ever discovered, I should assume that tlie twist in the West Cornwall granite began very early, and that it interfered with the structural development of E. and W. veins which was taking place in less disturbed circumstances in the rest of Cornwall. As to tin streams, my belief has long been that stream-tin — so fine in its quality, so peculiar in its structure — owes its origin to influences different from those Uiat have formed tin lodes, and is most probably a surface formation, one of the fragmentary remains of the vanished surface beds of the granite. But this should form a separate subject in itself. I < only remark here, that it is entirely in harmony with this view, that in the district where we find the surface beds most shattered, and destroyed, and washed away, we should find the most abundant de- posit of stream-tin ; for this has been nature s great stamping-mill, and our tin streams are its washings. One result of this view would be that the St. Just lodes are more recent than the chief part of tbe of the Land's End Oranite. 151 Cornish lodes; i.e. those on N.E. and S.W. lines. Yes, we should be obliged to refer them to a later period of quiet which followed the disturbing twist in the granite. I feel justified and encouraged in this opinion by the fact that Mr. Carne, in his paper " On Veins," has previously come to this conclusion on entirely separate grounds. There is one little bit of granite still unaccounted for; namely, that bit of the Lands End district west of a line drawn from Whitsand Bay to the Logan Rock. I believe this to be the latest of the whole, and that it was rolled or poured out as a separate bed* from under the southrcastern part after it was hardened, and still retains the structure common to beds of basalt. (Read at Annual Meetingy October 20th, 1874, by the Cv/rator.) REMARKS ON THE LODE AT WHEAL MARY ANN, MENHENIOT. Bt C. LeNevs F08TEB, aA.y D.sa, f.g.s. Some weeks ago I was underground at Wheal Mary Ann 9 and I there observed certain peculiarities in the lode which, I think, are worthy of being recorded, especially as the mine is on the point of being abandoned, and further observation will be impossible — at all events, for some years. It is true that the peculiarities of Wheal Mary Ann have not escaped the observant eye of Mr. Henwood, who has described the lode in the Trans- actions of this Society,* and also in the Journal of the Royal Institution of Cornwall.\ Mr. Giles has also written upon the same subject in our Trans- actionSjl and so has Mr. Salmon in the Mining and Smelting Magazine.^ However, in no published account have I been able to find any cross-section showing the structure of the lode, and as I can supply this omission, I have no hesitation in going over what may appear to some persons an old story. The lode runs a few degrees east of true north, and dips east at an angle of 60** to 80**. The flatter parts • Vol. viii. p. 704. f 1861, p. 42. t Vol. vii. p. 202. § Vol. ii. 1862, p. 218. The Lode al Wheal Mary Ann. 163 of the lode are generally poor, and filled with frag- ments of killas, or clay-slate, which constitutes the surrounding rock or " country." I need not dwell, however, on this point, as it is a common occurrence, and can easily be explfuned mechanically. I proceed at once to the main subject of my paper, in which I shall first describe the appearances shown under- ground at Wheal Mary Ann, and then point out what are the conclusions that may be drawn as to the formation of the lode. I greatly regret that I could only make observations over a very small extent of the lode. I simply saw one end at the 350 fathoms level, and one set of stopes, the only workings going on ; but the facts observed were so clear, that I feel almost sure that my opinions would be confirmed, rather than shaken, by additional evidence. DuatuM No. 1. 154 The Lode at Wheal Mary Ann. Diagram No. 1 shows a characteristic section of the lode as seen in the 350 fathom leveL We have, first of all, the two walls of killas; then, proceeding inwards from each wall, the